Rebar Weight Calculator
Calculate the approximate weight of steel reinforcing bar from its size, length and quantity. Choose metric or US rebar sizes to see total weight, weight per bar and weight per unit length.
How to use the rebar weight calculator
Start by choosing either Metric or US measurements. Select the rebar size, enter the length of each bar and then enter the number of bars you need.
The calculator shows the total estimated rebar weight, the weight of each individual bar and the weight per metre or per foot. It also displays the equivalent total weight in the alternative measurement system.
If your reinforcing bar is not one of the standard sizes shown, select Custom diameter and enter the diameter manually.
Rebar weight formula
Rebar weight is calculated from the cross-sectional area of the steel bar, its length and the density of steel.
Weight = cross-sectional area × length × steel density
For a round bar, the cross-sectional area is:
Area = π × diameter² ÷ 4
CalcAtlas uses a nominal steel density of approximately 7,850 kg/m³.
For reference, see the NIST publication on the physical properties of structural steels .
Example rebar weight calculation
Suppose you have 10 reinforcing bars that are 12 mm in diameter and 6 metres long.
- Rebar size: 12 mm
- Length of each bar: 6 m
- Quantity: 10
The estimated weight is approximately:
- 0.888 kg per metre
- 5.33 kg per 6 metre bar
- 53.27 kg for 10 bars
Metric rebar weight table
The table below shows approximate weights for common metric reinforcing bar diameters.
| Rebar diameter | Approx. weight per metre |
|---|---|
| 6 mm | 0.222 kg/m |
| 8 mm | 0.395 kg/m |
| 10 mm | 0.617 kg/m |
| 12 mm | 0.888 kg/m |
| 16 mm | 1.578 kg/m |
| 20 mm | 2.466 kg/m |
| 25 mm | 3.853 kg/m |
| 32 mm | 6.313 kg/m |
US reinforcing-bar sizes and nominal dimensions are standardized industry values. For further information about reinforcing steel and US rebar standards, see the Concrete Reinforcing Steel Institute guidance on reinforcing steel .
US rebar size and weight table
US reinforcing bars are commonly identified by bar number. The bar number relates approximately to the nominal diameter in eighths of an inch.
| Bar size | Nominal diameter | Approx. weight |
|---|---|---|
| #3 | 0.375 in | 0.376 lb/ft |
| #4 | 0.500 in | 0.668 lb/ft |
| #5 | 0.625 in | 1.043 lb/ft |
| #6 | 0.750 in | 1.502 lb/ft |
| #7 | 0.875 in | 2.044 lb/ft |
| #8 | 1.000 in | 2.670 lb/ft |
| #9 | 1.128 in | 3.400 lb/ft |
| #10 | 1.270 in | 4.303 lb/ft |
| #11 | 1.410 in | 5.313 lb/ft |
How accurate is the rebar weight calculation?
The calculator provides an estimate based on nominal bar dimensions and a steel density of approximately 7,850 kg/m³. Actual reinforcing bar weight can vary slightly because of manufacturing tolerances and applicable standards.
For purchasing, structural design or other critical work, use the dimensions and mass specified by the relevant manufacturer, supplier or engineering standard.
Rebar weight calculator FAQs
How do I calculate the weight of rebar?
Rebar weight can be estimated by calculating the cross-sectional area of the bar and multiplying it by its length and the density of steel. This calculator performs those calculations automatically.
How much does 12 mm rebar weigh?
A 12 mm steel reinforcing bar weighs approximately 0.888 kg per metre. A 6 metre length therefore weighs about 5.33 kg.
How much does #4 rebar weigh?
Standard US #4 rebar has a nominal diameter of 0.500 inches and weighs approximately 0.668 lb per foot.
Can I calculate a non-standard rebar diameter?
Yes. Select Custom diameter in the calculator and enter the required diameter in millimetres when using Metric mode or inches when using US mode.
Does rebar grade change its weight?
Rebar grade primarily describes strength rather than bar dimensions. Bars with the same nominal diameter and material density therefore have approximately the same weight, although actual manufactured weights may vary slightly.