Calculate the weight of steel bars, rebar, plates, sheets, pipes and hollow sections from their dimensions. This free steel weight calculator shows weight per metre, weight per piece and total steel weight in kilograms, pounds and metric tonnes.
Steel Weight Calculator
Calculate theoretical steel weight from shape, dimensions, length, density and quantity.
Calculation:
Material density:
This is a theoretical estimate based on the dimensions and density entered.
How to Calculate Steel Weight
Steel weight is calculated from the material's volume and density. The shape of the steel determines how its volume is calculated. A round bar uses a cylindrical formula, while a plate uses a rectangular volume formula. A pipe requires the hollow area to be calculated by subtracting the inside diameter from the outside diameter.
The default density used by this calculator is 7,850 kg/m3, which is commonly used for estimating the weight of mild and carbon steel. If you know the density of a different steel grade, you can enter it in the calculator.
Steel Weight Formulas by Shape
| Steel shape | Weight calculation |
|---|---|
| Round bar / rebar | Diameter squared ÷ 162.2 × length in metres |
| Square bar | Side squared × length × 0.00785 |
| Flat bar / plate | Width × thickness × length × 0.00785 |
| Round pipe / tube | π ÷ 4 × (outside diameter squared − inside diameter squared) × length × density |
| Hollow section | Outer cross-sectional area − inner cross-sectional area |
For the common round rebar shortcut, diameter is measured in millimetres and length is measured in metres. Dividing the diameter squared by 162.2 gives an approximate weight in kilograms per metre.
Example: Calculate the Weight of 16 mm Rebar
Suppose you have two 16 mm steel reinforcing bars, each 12 metres long. The approximate weight per metre can be calculated as follows:
Weight per metre: 16 squared ÷ 162.2 = 1.578 kg/m
Weight per bar: 1.578 × 12 = 18.94 kg
Total weight: 18.94 × 2 = 37.88 kg
The calculator uses the full volume and density calculation, so its result may differ slightly from the rounded shortcut formula.
Common Steel Rebar Weight Chart
The following values are approximate theoretical weights based on a steel density of 7,850 kg/m3.
| Bar diameter | Weight per metre | Weight per 12 m bar |
|---|---|---|
| 8 mm | 0.395 kg | 4.74 kg |
| 10 mm | 0.617 kg | 7.40 kg |
| 12 mm | 0.888 kg | 10.66 kg |
| 16 mm | 1.578 kg | 18.94 kg |
| 20 mm | 2.466 kg | 29.59 kg |
| 25 mm | 3.853 kg | 46.24 kg |
| 32 mm | 6.316 kg | 75.79 kg |
Read also: Length of Steel Bar in Different Countries
Frequently Asked Questions
How do I calculate the weight of steel?
Calculate the volume of the steel and multiply it by its density. For a common steel density of 7,850 kg/m3, the formula is steel weight = volume × 7,850. The shape determines how the volume is calculated.
What is the density of steel in kg/m3?
A commonly used estimating density for mild and carbon steel is 7,850 kg/m3. Different steel grades and alloys can have different densities, so use the manufacturer's value when an exact result is required.
How much does a 12 mm steel bar weigh per metre?
A 12 mm round steel bar weighs approximately 0.888 kg per metre when using a density of 7,850 kg/m3.
What is the formula for steel rebar weight?
For round rebar, the commonly used shortcut is diameter squared ÷ 162.2. Enter the diameter in millimetres to obtain the approximate weight in kilograms per metre.
How do I calculate steel plate weight?
Calculate the plate volume by multiplying its length, width and thickness. Then multiply the volume by the steel density. Make sure all dimensions are converted to consistent units before calculating.
How do I calculate the weight of a steel pipe?
Calculate the outside circular area and subtract the inside circular area. Multiply the resulting steel cross-sectional area by the pipe length and steel density to obtain the theoretical weight.
Does this calculator give the exact delivered steel weight?
No. It provides a theoretical weight based on the dimensions and density entered. Actual supplied weight can vary because of dimensional tolerances, coatings, manufacturing differences and the specific steel grade.
Can I calculate steel weight in pounds?
Yes. The calculator provides the total steel weight in kilograms, pounds and metric tonnes.