A fence estimate involves five connected calculations based on three core measurements: fence length, height, and post spacing. Change any one of these inputs, and the required materials and total cost change with it. Many fence calculators handle only part of the job, leaving gaps in the material list and budget. Accurate estimating also means accounting for gravel boards and gate posts, two components often missing from basic calculations.
The calculations below connect fence dimensions to post quantities, panel counts, gravel boards, gate posts, and material costs, giving you a more complete estimate before work begins.
To estimate a fence, work in this order. Posts = ceil(run length ÷ post spacing) + 1. Bays = posts − 1. Rails = bays × rails per bay. Pickets or boards = run length in inches ÷ (board width + gap), then add waste. Post length = fence height + burial depth, where burial is at least one-third of the above-ground height and never less than 24 inches. Concrete per post = hole volume − post volume, converted to bags at the yield printed on the bag.
Those six formulas produce the bill of materials. Everything else — cost, paint, removal, gates — is derived from them rather than calculated independently. A fence estimator that asks for material cost without first asking for post spacing is guessing.
The three lengths of a fence — and why confusing them is the expensive mistake
Every fence estimate begins with a length, and there are three different lengths in play. They are not interchangeable, and using the wrong one produces an error that compounds through every material line.
- Run length — the linear distance along the fence line, measured on the ground. This is what you feed into the post, rail and picket formulas.
- Fence area — run length multiplied by height. This is what you feed into paint, stain and cladding calculations. It is a two-dimensional quantity in square feet or square metres.
- Developed length — the length of the fence surface if you could lay it flat, which differs from run length on sloped ground because a stepped or racked panel covers more surface than its horizontal projection.
The common error is buying paint from the run length. A 100 ft run of 6 ft fence is not 100 ft² of paint surface — it is 600 ft² per side, and 1,200 ft² if you are painting both sides. The error factor is the fence height, which means the mistake gets worse as the fence gets taller.
On a slope, the developed length is what governs material because panels are installed either racked (following the slope) or stepped (level panels with a small step at each post). A stepped fence uses the same number of panels as the flat run, but each panel is trimmed, so the waste per panel rises. Racked fencing is only possible on gentle gradients; beyond about 10 degrees, most panel systems must be stepped.
A fence has three distinct lengths: run length (for posts, rails and boards), fence area (for paint and stain), and developed length (for panel surface on sloped ground). Confusing run length with area understates paint by a factor equal to the fence height.
The seven components, labelled
Every fence, regardless of material, is assembled from the same seven roles. The names change — a "picket" in the US is a "board" in the UK, and a "panel" in one system is a "section" in another — but the function is identical.
| Component | Function | Counted from | Common unit |
|---|---|---|---|
| Post | Carries the load; the structural member | Run length ÷ spacing, plus one | Each (sold by length) |
| Rail | Horizontal member that ties posts and carries boards | Bays × rails per bay | Each (sold by length) |
| Board / picket | The infill that provides privacy or containment | Run in inches ÷ (width + gap) | Each, or linear measure |
| Panel | A pre-assembled bay, used with slotted posts | Bays, or run ÷ panel width | Each |
| Gravel board | Lifts timber off the ground; a replaceable sacrificial base | Run length (continuous) | Each, by length |
| Post mix / concrete | Fixes the post and resists lateral load | Hole volume − post volume | Bags or cubic measure |
| Gate | Access; requires its own heavier posts | Each opening | Each, plus hardware |
The gravel board is the only component whose primary job is to fail first. It is designed to be replaced, which is why concrete gravel boards outlast the timber panels above them.
Panel types and what each costs you
Four panel families cover almost every residential fence. They differ in the number of boards per bay, the waste profile, and whether the panel is a pre-built unit or assembled on site. The choice changes the board count, the rail count and the labour hours — sometimes by a factor of two.
| Panel type | Boards per 6 ft bay | Rails per bay | Privacy | Waste profile |
|---|---|---|---|---|
| Closeboard (vertical) | 17–19 | 3 | Full | Low — boards cut at post only |
| Lap panel (horizontal) | 8–10 | 0 (framed) | Full | Very low — pre-assembled |
| Board-on-board | 28–34 | 3 | Full, with overlap | High — alternating layers double the count |
| Chain link | — | 1 top rail | None | Low — fabric sold in rolls with fixed height |
Board counts assume a 6 ft bay and standard board widths: 5½ in for closeboard and board-on-board, 6 in effective coverage for lap. A 5½ in board with a ½ in gap covers 6 in, so a 72 in bay takes 12 boards plus a starter — the standard 17–19 range allows for the overlap on closeboard.
The practical consequence: board-on-board roughly doubles the board cost per bay for the same privacy, in exchange for a stronger visual and better wind performance. Closeboard is the middle option — full privacy at a moderate board count, but the boards are nailed to rails on site, so labour hours are higher than a pre-built lap panel. A lap panel is the cheapest full-privacy option per bay because the panel arrives assembled and slots into grooved posts.
Post types and post length
Three post materials dominate: timber, concrete and steel. Each changes the fixing method, the lifespan, and — critically — whether a gravel board can be used at all.
| Post type | Typical size | Lifespan | Fixing method | Gravel board compatible? |
|---|---|---|---|---|
| Timber (pressure-treated) | 4×4 in / 100×100 mm | 10–15 years | Nailed or screwed through rails; boards fixed to rails | Yes — timber or concrete |
| Concrete | 4×4 in slotted, or 120×120 mm | 25–40 years | Panels slot into grooves; boards screwed to battens | Yes — concrete preferred |
| Steel (galvanised or powder-coated) | 60×60 mm or 70×70 mm | 20–30 years | Brackets or channels; panels bolt on | Yes, with an adapter |
One retail system specifies that a timber post cannot take a gravel board option, while a concrete post can — because the panel hangs from the post rather than sitting on a rail. That is a design constraint, not a material limitation, and it is the kind of detail a generic calculator cannot know.
Post length is the sum of three numbers, not two. Most estimators remember above-ground height and burial depth and forget the gravel base.
Dburial = the larger of Habove ÷ 3, 24 in, or frost depth + 4 in
For a 6 ft fence with 2 ft burial, the post is 8 ft. That is why 8 ft posts are the standard retail length for a 6 ft fence. Add a 12 in gravel board and the above-ground height becomes 7 ft, so the post needs to be 9 ft — which usually means buying a 10 ft post and cutting it, or using a concrete post in a longer length.
Gravel boards are commonly 150 mm or 300 mm high. A 300 mm board raises the bottom of the panel by 300 mm, so the total fence height above ground increases by 300 mm. If you sized the post for the panel height alone, the post is now too short to give the required burial. Recalculate the post length after choosing the gravel board, not before.
Post spacing: the 8 ft rule and its exceptions
For timber fences, 8 ft is the standard maximum post spacing. It is not a rule of physics; it is the length at which a 4×4 post in a 2 ft footing still resists the lateral load from wind on a 6 ft panel without excessive deflection. Every other material has a different limit.
| Fence material | Typical max post spacing | What governs the limit |
|---|---|---|
| Timber closeboard / board-on-board | 8 ft (2.4 m) | Wind load on a solid panel; rail span |
| Timber post-and-rail | 8–10 ft | Rail length and stock size |
| Lap panel with concrete posts | 6 ft (1.83 m) | Panel width, not post strength |
| Chain link | 10 ft for 4 ft high; 6–8 ft for 8 ft high | Wind load on fabric; top rail sag |
| Vinyl / composite | 6–8 ft | Manufacturer's panel width |
| Steel estate fencing | Up to 10 ft | Post section and ground conditions |
The chain link row is the one most often got wrong. A 4 ft chain link fence can span 10 ft between posts, but an 8 ft fence needs 6 ft spacing because the fabric presents more than twice the sail area. Spacing that is fine at one height is not fine at another.
The post count formula rounds the bay count up, then adds one for the closing post. That produces an actual spacing slightly smaller than the maximum, which is what you want: a run that divides evenly is rare, and a short final bay looks wrong.
A 100 ft run at 8 ft spacing gives 100 ÷ 8 = 12.5 bays, which rounds to 13. Thirteen bays need 14 posts, and 100 ÷ 13 = 7.69 ft actual spacing. The 14-post answer is the one most calculators produce; the 7.69 ft actual spacing is the one most of them omit, and it is the number you need when marking out.
Post depth: two rules, and the frost line wins
Two independent rules govern how deep a post goes. The structural rule is one-third of the above-ground height. The geotechnical rule is that the footing must sit below the local frost line. In mild climates they agree; in cold climates the frost line can double the depth — and the concrete with it.
| Rule | What it says | Example: 6 ft fence |
|---|---|---|
| One-third rule | Bury at least one-third of the above-ground height | 24 in |
| One-third to one-half range | Some guidance widens this to 1/3–1/2 for exposed sites | 24–36 in |
| Minimum depth | Never less than 24 in regardless of height | 24 in |
| Frost line | Footing must extend below the frost line, often +4 to 6 in | 36–60 in in cold zones |
Sources: one-third rule for most soils; 24–36 in for a 6 ft fence; frost depth governs where it exceeds the structural minimum, with some jurisdictions requiring footings 6 in below the frost line.
The concrete consequence is larger than the depth ratio suggests, because hole volume grows with the square of the diameter and the diameter usually grows too. A 10 in hole at 24 in holds 1.36 ft³; the same hole at 48 in holds 2.73 ft³ — double. If the diameter also goes from 10 in to 12 in, the volume more than doubles again.
When the ground freezes from the top down, ice grips the post and the concrete footing and lifts the whole assembly. A footing that sits entirely within the freeze zone will move every winter. The damage is not gradual settlement; it is a post that is 2 in higher in March than it was in November, with a panel that no longer lines up. In a cold climate, the frost line is not a suggestion.
Concrete: hole minus post, then bags
The concrete volume is the volume of the hole minus the volume of the post that occupies it. Skipping the subtraction is the most common concrete overestimate on a fence — it adds 15–20% to the bag count on a typical 4×4 post in a 10 in hole.
| Bag size | Yield (ft³) | Yield (m³) | Bags per ft³ |
|---|---|---|---|
| 40 lb | 0.30 | 0.0085 | 3.33 |
| 50 lb | 0.375 | 0.0106 | 2.67 |
| 60 lb | 0.45 | 0.0127 | 2.22 |
| 80 lb | 0.60 | 0.0170 | 1.67 |
| 90 lb | 0.675 | 0.0191 | 1.48 |
Bag yields are nominal and vary by manufacturer. Always check the yield printed on the bag you are buying; the figures above are the industry-standard approximations for packaged concrete mix.
One post, then fifteen
Hole: Ø 10 in (0.833 ft), depth 30 in (2.5 ft) Post: 3.5 × 3.5 in (0.292 ft), depth 2.5 ft
Vhole = π × 0.4167² × 2.5 = 1.363 ft³. Vpost = 0.292 × 0.292 × 2.5 = 0.213 ft³. Concrete = 1.150 ft³ per post. For 15 posts: 17.25 ft³. At 0.60 ft³ per 80 lb bag, that is 28.75 bags, so 29 bags — or 30 with a 5% allowance for spillage.
Answer: ≈ 2 bags per post; 29–30 bags total
That matches the field rule of thumb: a 4×4 post in a 10 in hole, 30 in deep, takes about 2 bags of 80 lb mix. A 6×6 post in a 12 in hole, 48 in deep, takes 3–4. The rule of thumb is derived from exactly the calculation above; the calculation is worth doing when your dimensions differ from the standard.
Rails, pickets and boards
Rails are counted from bays; boards are counted from coverage. The two are independent, which is why a fence with more rails does not necessarily need more boards.
Rails per bay is a design choice with a structural floor. Two rails (top and bottom) is the minimum for a fence under 6 ft; three rails is standard for 6 ft and taller, and is effectively mandatory for closeboard because the boards are nailed to every rail. A 6 ft closeboard fence with two rails will cup and bow within a season.
| Fence height | Rails per bay | Reason |
|---|---|---|
| Up to 4 ft | 2 | Top and bottom are sufficient; low wind load |
| 4–6 ft | 3 | Mid-rail prevents board cupping |
| Over 6 ft | 3–4 | Additional rail resists wind and board movement |
| Board-on-board, any height | 3 | Each layer must be fixed to every rail |
Board count is where nominal versus actual size matters. A "6 inch" board is usually 5½ in actual width. With a ½ in gap, each board covers 6 in, so a 72 in bay takes 12 boards plus a starter board — 13 per bay, or about 2.17 per linear foot. Tight-butted boards at 5½ in cover take 13 per bay plus a starter, or about 2.18 per foot. The difference between a ½ in gap and no gap is small in count but large in privacy and wind load.
Board-on-board uses two layers, offset so that the second layer covers the gaps in the first. The board count roughly doubles — from about 2.2 per foot to about 4.4 per foot for the same coverage. A calculator that applies the side-by-side formula to a board-on-board fence will under-order by half. The multiplier is not 2.0 exactly, because the offset layer uses slightly wider spacing; plan for 2.5–2.7 boards per linear foot in practice.
Gravel boards: the component most calculators omit
A gravel board is a timber or concrete plank fitted between the bottom of the fence panel and the ground. Its job is to keep the panel out of soil and standing water, which is where rot starts. It is a sacrificial component: it is designed to fail before the panel does, and to be replaced without dismantling the fence.
| Property | Timber gravel board | Concrete gravel board |
|---|---|---|
| Typical height | 150 mm (6 in) | 150 mm or 300 mm (6 or 12 in) |
| Lifespan | 5–10 years | 25+ years |
| Rot risk | High — it is in contact with soil | None |
| Effect on fence height | Raises panel by board height | Raises panel by board height |
| Compatible with timber posts | Yes | Yes, with a post adapter or notched post |
| Compatible with concrete posts | Yes | Yes — the standard pairing |
Common heights are 150 mm and 300 mm. A 300 mm board raises the panel by 300 mm, which increases the total above-ground fence height and therefore the required post length.
Two consequences follow, and both are missing from most calculators. First, the gravel board is counted by run length, not by bay, because it runs continuously behind the posts. Second, choosing a 300 mm concrete board instead of a 150 mm timber board changes three other numbers: the post length (taller above ground), the panel height (shorter panel for the same total height), and the lifespan of the base (longer than the panel above it, which is the point).
A gravel board is a timber or concrete plank at the base of a fence that separates the panel from soil and standing water, reducing rot. Common heights are 150 mm and 300 mm. It raises the panel by its own height, so total fence height and required post length both increase when a gravel board is specified.
If you sized the post as fence height plus burial, and then added a gravel board, the post is now short. A 6 ft panel on a 300 mm gravel board needs 6.98 ft above ground, not 6 ft. With 2 ft burial, the post is 8.98 ft — so an 8 ft post no longer works. Recalculate after the gravel board is chosen, not before.
Gates: the post schedule changes
A gate is the heaviest point load on a fence line. It is a cantilever: the hinges transfer the gate's weight and any wind load into two posts that must resist both pull-out and rotation. That is why gate posts are usually one size up from line posts, set deeper, and counted separately.
| Gate width | Post size (timber) | Minimum burial | Concrete per post |
|---|---|---|---|
| Up to 3 ft (pedestrian) | 4×4 in | 24–30 in | 2–3 bags of 80 lb |
| 3–5 ft (standard garden) | 4×4 or 5×5 in | 30–36 in | 3–4 bags of 80 lb |
| 5–8 ft (driveway single) | 6×6 in | 36–48 in | 4–6 bags of 80 lb |
| 8–16 ft (driveway double) | 6×6 in or steel | 48 in+ | 6+ bags per post |
Gate posts carry a load the line posts do not, so they are not interchangeable. Reusing a line post schedule for a gate is the most common cause of a sagging gate within a year.
The gate also changes the post count arithmetic. A gate opening interrupts the run, so the net fence length is the run length minus the gate widths. The gate posts are then added to the post count, but they may be shared with the last line post on each side — which means the count is not simply "line posts plus two."
For a 100 ft run with two 3 ft gates, the net run is 94 ft. At 8 ft spacing, 94 ÷ 8 = 11.75, so 12 bays and 13 posts — but the two gates sit at specific points, so the 13 posts are the two gate posts plus the line posts between and beyond them. The gate widths reduce the material run but do not reduce the gate post requirement, which is why gate openings are a net cost add even though they reduce the length of panel.
Fence area and paint: area is not length
Paint, stain and wood preserver are specified by coverage per unit area, not per unit length. The area of a fence is the run length multiplied by the height, and then multiplied again by the number of sides you intend to coat.
The surface factor is the part most calculators omit. A flat panel of 600 ft² has 600 ft² of surface. A closeboard fence of the same nominal area has more, because each board presents two edges and an overlap. The extra is small per board and large over a run: 10–15% on closeboard, near zero on a flat lap panel.
| Product | Typical coverage | Coats | 100 ft × 6 ft, one side |
|---|---|---|---|
| Fence paint (water-based) | 10–13 m²/L (100–130 ft²/L) | 2 | ≈ 9–12 L |
| Wood stain / preserver | 6–10 m²/L (65–110 ft²/L) | 1–2 | ≈ 11–18 L |
| Spray / airless | Higher, but 15–25% overspray | 1–2 | Same or more |
Coverage varies by product and by surface roughness. Rough-sawn timber absorbs significantly more than planed timber, sometimes 30–40% more on a first coat.
Two sides is not the same as double the paint on one side, because the far side of a closeboard fence is usually rougher and more absorbent. A fence that is painted on the "good" side only will weather faster on the other, and the panels will cup toward the drier face. If you are coating both sides, budget for the full two-sided area, not a discount for shared edges.
Cost: four price tiers, not one
Fence costs are usually quoted as a single "per linear foot" figure, and that figure is almost meaningless without knowing what it includes. The same fence can be quoted at $12/ft and $45/ft in the same market, and both quotes can be honest — they are pricing different scopes.
| Tier | What is included | Typical range (US, 2026) |
|---|---|---|
| Materials only | Posts, rails, boards, concrete, fixings — no labour | $8–25 / lf depending on material |
| Materials + labour | The above, installed, no removal | $10–55 / lf |
| Installed + removal | Installation plus disposal of the old fence | Add $3–8 / lf |
| Installed + removal + gates | The above plus gates and hardware | Add $150–600 per gate |
| Material | Height | Installed cost per linear foot | Lifespan |
|---|---|---|---|
| Chain link | 4 ft | $10–25 | 20–30 years |
| Wood privacy | 6 ft | $20–45 | 15–20 years |
| Vinyl | 6 ft | $25–40 | 20–30 years |
| Aluminium | 6 ft | $30–55 | 25–30 years |
Cost ranges are US residential installed prices for 2026 and vary substantially by region, site access, terrain and gate count. Chain link is consistently the cheapest material per linear foot; aluminium and composite are the most expensive.
Three cost drivers are invisible in a per-foot rate and should be asked about explicitly. Site access — a fence that can only be reached through a house costs more than one with a clear side gate. Terrain — a slope that forces stepped panels adds cutting and waste. Old fence condition — a fence set in concrete that has to be broken out costs more to remove than one set in soil.
Chain link is priced differently
Chain link is not priced like a panel fence because it is not assembled from bays. It uses terminal posts at every end, corner and gate, and line posts in between; the fabric is held by tension bars and tension bands at the terminal posts, and by ties at the line posts. A chain link estimate that counts "posts" without splitting terminal from line will under-order the expensive posts and the tension hardware.
| Component | Where it is used | Counted from |
|---|---|---|
| Terminal post | Ends, corners, gate openings | Number of ends + corners + gate posts |
| Line post | Intermediate supports | Bays − terminal posts |
| Top rail | Continuous along the run | Run length ÷ rail length |
| Tension bar | One per terminal post | Terminal posts |
| Tension band | Several per terminal post | Typically 3–4 per terminal |
| Fabric | Continuous, by height | Run length × height, in rolls |
Fabric is sold in rolls of fixed height and length, so the number of rolls is driven by height and run, not by post count. A 4 ft fence and a 6 ft fence of the same run use the same number of posts but different fabric.
Removal is its own line
Removing an existing fence is not proportional to the new fence's length, because the cost is dominated by what the old posts are set in. Timber posts in soil can often be pulled; posts in concrete have to be broken out, which can double the removal cost per post. A removal estimate that uses a single per-foot rate will be wrong on one of those two cases.
Waste is not uniform
A single "add 10%" line at the bottom of an estimate is better than nothing and worse than a component-by-component allowance. Different components waste at different rates, for different reasons.
| Component | Typical waste | Why |
|---|---|---|
| Boards / pickets | 10% | Cutting at posts, defects, cupping rejects |
| Rails | 5% | Cut at the final bay only; off-cuts often reusable |
| Posts | 0–2% | Bought at fixed length; no cutting waste unless height is non-standard |
| Panels | 10% | Breakage in transit, trimming at steps |
| Concrete | 5% | Spillage, over-dig, uneven hole diameter |
| Fixings | 10–15% | Dropped, stripped, or driven badly |
| Paint | 10% | Pot loss, roller absorption, second-coat touch-up |
The 10% board allowance is the industry standard, but it assumes a straight run with no steps. A stepped fence on a slope can push board waste to 15–20% because every panel is trimmed to a different height.
The asymmetry matters because posts are the most expensive single component per unit. Applying a blanket 10% to a 14-post order buys 1.4 extra posts — which is fine if you need one spare, but it is not a cutting allowance, because posts are not cut. The right allowance on posts is one spare, not a percentage.
Material waste on a fence is not uniform: boards and panels typically need 10%, rails about 5%, posts 0–2% (one spare is more useful than a percentage), concrete about 5%, and fixings 10–15%. A blanket percentage over-orders posts and under-orders boards on a stepped run.
Worked example: 100 ft × 6 ft closeboard privacy fence
This is the full chain, from run length to bag count and paint volume, for a realistic specification: 100 ft run, two 3 ft gates, 6 ft closeboard panels on a 300 mm concrete gravel board, timber posts at 8 ft maximum spacing, three rails per bay, mild climate with a 24 in frost depth.
| Step | Calculation | Result |
|---|---|---|
| 1. Net run | 100 − (2 × 3) | 94 ft |
| 2. Posts | ceil(94 ÷ 8) + 1 | 13 line + gate posts |
| 3. Bays | 13 − 1 | 12 |
| 4. Actual spacing | 94 ÷ 12 | 7.83 ft |
| 5. Rails | 12 × 3 | 36 |
| 6. Boards | 94 × 12 ÷ 6, +10% | 207 |
| 7. Gravel board | 94 ft continuous | 94 ft |
| 8. Post length | 6 ft + 0.98 ft board + 2 ft burial | 9 ft → buy 10 ft |
| 9. Concrete per post | π × 0.4167² × 2 − 0.213 | 0.88 ft³ |
| 10. Concrete total | 0.88 × 15 posts, +5% | 13.9 ft³ → 24 bags of 80 lb |
| 11. Paint area, one side | 94 × 6.98 × 1.12 | 735 ft² |
| 12. Paint, two sides, 2 coats | 735 × 2 × 2 ÷ 110 | ≈ 27 L |
The post count is 13 line posts plus the two gate posts, but the gate posts may coincide with line posts at the opening. In this example 15 posts are set, of which two are gate posts. Post length is 9 ft because the 300 mm gravel board raises the panel; a 10 ft post is bought and cut down.
What you actually order
94 ft of fence · 15 posts · 36 rails · 207 boards · 94 ft gravel board · 24 bags concrete · 27 L paint
At a materials-only cost of roughly $12–18 per linear foot for closeboard, the material bill sits around $1,130–$1,690. Installed, at $20–45 per linear foot, the same fence is $1,880–$4,230. The gap between those two figures is labour, plant and profit — not materials.
Answer: 15 posts, 36 rails, 207 boards, 24 bags, 27 L
The two numbers worth noticing are the post length and the board count. The post is 9 ft because of the gravel board, not 8 ft — a detail that a calculator without a gravel board field will get wrong. The board count is 207, not 188, because the 10% allowance applies to boards but not to posts.
Common mistakes and a verification routine
Each mistake below has a predictable direction and a measurable size, which makes it recognisable in an estimate that looks wrong.
| Mistake | What it does | Direction | Typical size |
|---|---|---|---|
| Using run length as area for paint | Understates paint by the height factor | 6× low on a 6 ft fence | 100 ft² instead of 600 ft² |
| Forgetting the post volume in concrete | Over-orders concrete | 10–20% high | +3–5 bags on 15 posts |
| Using 8 ft posts with a 300 mm gravel board | Post too short for burial | Structural | 1 ft short |
| Applying a blanket 10% to posts | Over-orders the most expensive item | Too high | +1–2 posts |
| Counting boards without waste | Short on the last bay | Too low | −10% |
| Using the side-by-side board formula for board-on-board | Half the boards needed | 50% low | −2.2 boards/ft |
| Reusing line-post depth for gate posts | Gate sags within a year | Structural | −6–12 in burial |
| Ignoring the frost line | Post heaves every winter | Structural | −24 in in cold zones |
| Pricing chain link by post count only | Misses terminal posts and tension hardware | Too low | −15–25% |
| Quoting a single per-foot rate | Hides what is included | Ambiguous | 2× spread |
(1) Confirm the three lengths — run, area and developed — are not being used interchangeably. (2) Confirm the post length includes the gravel board. (3) Confirm the concrete calculation subtracts the post volume. (4) Confirm the board count has a waste allowance and the post count does not. (5) Confirm the cost figure states whether it includes labour, removal and gates. Those five checks catch almost every estimating error that survives arithmetic.
The fastest single check is the post count. Divide the run by the spacing, round up, add one. If the estimate's post count differs from that number by more than the gate posts, either the net run is wrong or the spacing is not what you think it is. Every other material line is derived from the post count or the run length, so an error there propagates to the whole bill.
Questions people actually search for
Twelve answers, each self-contained. Tap to expand.
How many fence posts do I need for a 100 ft fence?
At an 8 ft maximum spacing, 14 posts. Divide 100 by 8 to get 12.5 bays, round up to 13 bays, then add one for the closing post. The actual spacing becomes 100 ÷ 13 = 7.69 ft, which is slightly tighter than the maximum and avoids a short final bay. If the run includes gates, subtract the gate widths first and add the gate posts separately.
How deep should fence posts be buried?
At least one-third of the above-ground height, and never less than 24 inches. A 6 ft fence therefore needs 24 in minimum, and some guidance recommends 24–36 in for exposed sites. In cold climates the local frost line overrides the one-third rule — footings must extend below it, often with an extra 4–6 in, which can push a 6 ft fence to 48 in or more.
How many bags of concrete per fence post?
A typical 4×4 post in a 10 in hole, 30 in deep, takes about 2 bags of 80 lb mix. A 6×6 post in a 12 in hole, 48 in deep, takes 3–4 bags. The exact number comes from hole volume minus post volume, divided by the bag yield: an 80 lb bag yields about 0.60 ft³, a 60 lb bag about 0.45 ft³, and a 40 lb bag about 0.30 ft³.
What is a gravel board and do I need one?
A gravel board is a timber or concrete plank at the base of the fence that keeps the panel out of soil and standing water, where rot starts. It is a sacrificial component designed to be replaced without dismantling the fence. Concrete gravel boards last 25+ years and are the standard pairing with concrete posts. Common heights are 150 mm and 300 mm; a 300 mm board raises the panel and therefore the required post length.
How many fence boards or pickets per foot?
For standard 5½ in boards with a ½ in gap, each board covers 6 in, so you need about 2 boards per linear foot — 200 boards for a 100 ft run, plus 10% waste, so 220. For tight-butted boards the count is similar because the gap disappears but the coverage per board is the same. For board-on-board, roughly double it: plan for 2.5–2.7 boards per foot.
What is the maximum post spacing for a fence?
8 ft for timber privacy fencing is the standard maximum, governed by wind load on a solid panel and the rail span. Lap panels with concrete posts are typically limited to 6 ft by the panel width. Chain link can span 10 ft at 4 ft high but only 6–8 ft at 8 ft high, because the fabric's sail area more than doubles. Vinyl and composite follow the manufacturer's panel width, usually 6–8 ft.
How do I calculate fence paint?
Multiply run length by height to get area per side, then multiply by the number of sides and by a surface factor of about 1.12 for closeboard. Divide by the product's coverage per litre and multiply by the number of coats. A 100 ft × 6 ft fence is 600 ft² per side, 1,200 ft² for both sides, and roughly 9–12 litres of fence paint for two coats at 100–130 ft²/L.
Do gate posts need to be bigger than line posts?
Yes. A gate is a cantilever load, so gate posts are usually one size up and set deeper than line posts. A pedestrian gate up to 3 ft may use a 4×4 at 24–30 in; a 3–5 ft garden gate should use 4×4 or 5×5 at 30–36 in; a driveway gate of 5–8 ft needs a 6×6 at 36–48 in. Reusing a line-post schedule for a gate is the most common cause of a sagging gate.
How much does a fence cost per linear foot?
Installed US residential prices in 2026 run roughly $10–25/lf for 4 ft chain link, $20–45/lf for 6 ft wood privacy, $25–40/lf for vinyl and $30–55/lf for aluminium. Materials alone are typically $8–25/lf. Removal adds $3–8/lf and gates add $150–600 each. Always ask whether a quoted rate includes labour, removal and gates — the same fence can be quoted at $12/ft and $45/ft honestly.
How many rails does a 6 ft fence need?
Three rails per bay for a 6 ft closeboard or board-on-board fence. Two rails (top and bottom) is the minimum for fences under 6 ft; three is standard at 6 ft and above because the mid-rail prevents boards from cupping and bowing. Rails are counted as bays × rails per bay, so a 12-bay fence with three rails needs 36 rails.
What is the difference between a fence panel and a fence section?
Nothing structural. A panel is a pre-assembled bay that slots into grooved posts; a section or bay is the space between two posts, which may be filled by a panel or assembled on site from rails and boards. The distinction matters for ordering: a panel fence is counted in panels (one per bay), while a closeboard fence is counted in boards and rails.
How much waste should I add to a fence order?
10% on boards and panels, about 5% on rails, 0–2% on posts (buy one spare rather than a percentage), 5% on concrete and 10–15% on fixings. A stepped fence on a slope can push board waste to 15–20% because every panel is trimmed to a different height. A single blanket percentage over-orders posts and under-orders boards.
Estimate the whole fence, not one slice of it
Each tool in the set handles one part of the chain — posts and spacing, boards, concrete, gravel boards, gates, paint, cost and removal — and each returns the substituted arithmetic so the numbers can be checked by hand.
Post spacing Post hole concrete Full cost