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Rebar Weight

Estimate steel bar weight from diameter, length, quantity and steel density.

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The rebar weight calculator estimates the mass of circular steel reinforcing bars from bar diameter, individual bar length, quantity and steel density. It reports both the theoretical weight per meter and the total weight for the entered set of bars.

How it works

Enter the nominal bar diameter in millimeters, the length of one bar in meters, the number of bars and the steel density in kilograms per cubic meter. The calculator determines the circular cross-sectional area, converts square millimeters to square meters through the formula, calculates kilograms per meter, then multiplies by bar length and quantity.

The formula

Weight per meter (kg/m) = π × diameter² (mm²) ÷ 4 × steel density (kg/m³) ÷ 1,000,000. Total weight (kg) = weight per meter × bar length (m) × quantity.

Diameter is the circular bar diameter in millimeters. Length is the length of each bar in meters and quantity is the number of equal bars. Steel density is editable; the calculator defaults to 7850 kg/m³. The calculation is geometric and does not add laps, hooks, bends, chairs, couplers, cutting waste or fabrication tolerances.

Worked example

For 16 mm bars with density 7850 kg/m³, the theoretical weight is about 1.578 kg/m. Ten bars that are 12 m long therefore weigh about 1.578 × 12 × 10 = 189.4 kg using the calculator's unrounded internal value.

Use the result for preliminary quantity and logistics estimates. Reinforcement size, spacing, anchorage and detailing must come from the applicable structural design and drawings.

Frequently asked questions

Why can calculated rebar weight differ from delivered weight?

The result is a theoretical geometric estimate. Manufacturing tolerances, actual bar dimensions, coatings, fabrication details and weighing procedures can create differences.

Does the calculator include lap lengths and cutting waste?

No. Enter the effective bar length and quantity required by your takeoff, and add laps, anchorage, hooks and waste separately.

Can I change steel density?

Yes. The density field is editable. The calculator's default is 7850 kg/m³.

Last content reviewAugust 8, 2026
Editorial reviewHe-Sab Editorial Review

Sources and references

These sources are used to verify terminology, formulas, and information related to this calculator.