Calculate board feet, lumber cost, weight and linear feet for single boards, full stacks and mixed species. Nominal or actual dimensions, imperial or metric, with the formula printed on every result.
- Single Board
- Multi-Board Tally
- Cost Per Board Foot
- Weight Estimate
- Linear Feet
- Waste Factor
Add each board size as its own row. The calculator sums board feet, cost and weight across the whole stack.
Use this when you know the board feet you need and want to convert to linear feet at a fixed width and thickness.
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Enter your board dimensions, then press Calculate Board Feet.
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Tally breakdown
How to Calculate Board Feet
A board foot is 144 cubic inches of lumber — a piece 1 ft × 1 ft × 1 in. Every board foot calculation uses the same three inputs.
All inches
When length is in inches, divide by 144.
BF = T x W x L / 144
Length in feet
When length is in feet, divide by 12.
BF = T x W x L / 12
Multiple pieces
Multiply by quantity after finding the per-piece board footage.
BF total = BF piece x qty
Linear feet
Convert board feet back to linear length at a fixed width and thickness.
LF = BF x 12 / (T x W)
Hardwood lumber is bought and sold by nominal board feet — the rough-sawn dimensions before planing. A 2×4 is still billed as 2×4 even though its actual size is 1½ × 3½. If your supplier quotes actual dimensions, switch the dimension type above.
Worked Board Foot Examples
| Board | Dimensions (nominal) | Board feet | Notes |
|---|---|---|---|
| Standard 1×6 | 1 in × 6 in × 8 ft | 4.00 bf | Most common shelf and trim board |
| 2×4 stud | 2 in × 4 in × 8 ft | 5.33 bf | Wall framing — 5.33 bf per stud |
| 2×6 joist | 2 in × 6 in × 12 ft | 12.00 bf | Floor joist — 12 bf per piece |
| 4/4 oak plank | 1 in × 8 in × 10 ft | 6.67 bf | Hardwood sold by the board foot |
| 8/4 walnut slab | 2 in × 12 in × 6 ft | 12.00 bf | Thick stock — quarter system |
| 10 boards 1×6 × 8 ft | 1 in × 6 in × 8 ft × 10 | 40.00 bf | Bulk order example |
| Oak at $8.50/bf | 40 bf total | — | Cost = 40 × $8.50 = $340 |
| Pine at $3.20/bf | 100 bf total | — | Cost = 100 × $3.20 = $320 |
Nominal vs Actual Lumber Dimensions
The name on the label is not the size of the board. This is the single biggest source of ordering errors in lumber.
| Nominal | Actual (dressed) | Board feet factor | Common use |
|---|---|---|---|
| Dimensional lumber | |||
| 1×4 | 3/4 × 3½ | 0.333 bf/ft | Trim, shelving |
| 1×6 | 3/4 × 5½ | 0.500 bf/ft | Shelving, fascia |
| 2×4 | 1½ × 3½ | 0.667 bf/ft | Framing, studs |
| 2×6 | 1½ × 5½ | 1.000 bf/ft | Joists, rafters |
| 2×8 | 1½ × 7¼ | 1.333 bf/ft | Joists, beams |
| 2×10 | 1½ × 9¼ | 1.667 bf/ft | Headers, beams |
| Hardwood quarter thicknesses | |||
| 4/4 | 1 in rough | Per bf | Standard hardwood |
| 5/4 | 1¼ in rough | 1.25 × 4/4 bf | Stair treads |
| 6/4 | 1½ in rough | 1.5 × 4/4 bf | Table tops |
| 8/4 | 2 in rough | 2 × 4/4 bf | Thick stock |
Board feet follow the American Softwood Lumber Standard (nominal sizing) and NHLA grading rules (hardwood). The imperial board foot is defined as 144 cubic inches — approximately 2,360 cm³ or 0.00236 m³. Metric lumber is sold by actual volume in m³.
For quick estimates at the yard, remember that 1 board foot = 1 sq ft of 1-inch-thick lumber. So a 1×6 board gives 0.5 bf per linear foot, a 1×12 gives 1 bf per linear foot, and a 2×6 also gives 1 bf per linear foot. Add 10% waste for standard cuts and 15–20% for projects with many angled or mitred cuts.
People Also Ask
What is a board foot in simple terms?
A board foot is a volume measurement for lumber equal to 144 cubic inches — a board 1 foot long, 1 foot wide and 1 inch thick. If you stacked twelve 1-inch boards one foot square, you would have twelve board feet.
How do I calculate board feet for a 2×4×8?
Use the nominal dimensions: 2 × 4 × 8 ÷ 12 = 5.33 board feet. Even though the actual size is 1½ × 3½, you pay for the nominal 2×4. A full bunk of 2×4×8 studs (294 pieces) contains about 1,568 board feet.
What is the formula for board feet in inches?
If all three dimensions are in inches, the formula is Thickness × Width × Length ÷ 144. For example, a board 1 in × 6 in × 96 in = 576 ÷ 144 = 4 board feet. The 144 comes from 12 × 12 — the cubic inches in a board foot.
How many board feet are in a 2×6×12?
2 × 6 × 12 ÷ 12 = 12 board feet per piece. A 2×6 joist at 12 feet long contains exactly 12 board feet. At $6 per board foot, one joist costs $72.
What is the difference between board feet and linear feet?
Board feet measure volume — thickness × width × length. Linear feet measure length only, regardless of width or thickness. A 1×6 and a 2×12 can both be 8 linear feet long, but the 1×6 is 4 board feet and the 2×12 is 16 board feet. You buy lumber by board feet; you cut it by linear feet.
Do I use nominal or actual dimensions for board feet?
Use nominal dimensions for hardwood lumber and for most softwood sold by the board foot. Nominal is the rough-sawn size before planing. If your supplier quotes actual (dressed) sizes — common on some engineered and imported stock — switch the dimension type in the calculator to Actual.
How much waste should I add to a board foot order?
10% is standard for straight cuts and simple layouts. Add 15% for projects with angled cuts, and 20% for complex mitred work or when matching grain across multiple boards. The waste field in the calculator defaults to 10%.
How do I convert board feet to cubic metres?
Multiply board feet by 0.0023597 to get cubic metres. One board foot is 0.00236 m³. Going the other way, 1 m³ contains approximately 424 board feet. Metric lumber is usually sold directly in m³, so this conversion is mainly for cross-checking an imperial quote.
What does 4/4, 6/4 and 8/4 mean in lumber?
The numbers are quarter-inch increments of rough thickness. 4/4 = 1 inch rough, 5/4 = 1¼ inches, 6/4 = 1½ inches, 8/4 = 2 inches, 12/4 = 3 inches. Hardwoods are bought this way because thickness is the primary driver of both cost and structural capability.
Why does the calculator show both nominal and actual size?
Because board feet are priced on nominal size but the board you hold is actual size. Showing both prevents the common mistake of measuring a dressed 2×4 at 1½ × 3½ and ordering only half the lumber you need. The board feet figure always uses nominal unless you switch the setting.
Related Calculators
References
- American Softwood Lumber Standard, PS 20. U.S. Department of Commerce.
- NHLA Rules for the Measurement & Inspection of Hardwood & Cypress. National Hardwood Lumber Association.
- Wood Handbook — Wood as an Engineering Material. USDA Forest Service, Forest Products Laboratory.
- ASTM D9 — Standard Terminology Relating to Wood and Wood-Based Products. ASTM International.
- EN 1313-1 — Round and Sawn Timber: Permitted Deviations and Preferred Sizes. European Committee for Standardization.
Confirm board footage, grade and pricing against the supplier's tally sheet before placing a lumber order.