Rebar Calculator — Weight of Reinforcing Steel
Quickly find the weight of reinforcing steel bars for any construction project. Select or enter the rebar diameter, the length per bar and the quantity — the calculator returns weight per metre, weight per bar and total weight.
Rebar diameter
m
bars
Combined weight of all bars
- 1
Cross-section area
π × (6 mm)² = 113.1 mm²Area of the circular rebar cross-section drives the weight per metre. - 2
Weight per metre
113.1 mm² × 10⁻⁶ × 7,850 kg/m³ = 0.8878 kg/m - 3
Weight per bar
0.8878 kg/m × 6 m = 5.327 kg - 4
Total weight
5.327 kg × 20 bars = 106.54
How does this calculator work?
Weight per metre = (π/4) × (d/1000)² × 7850 kg/m, where d is diameter in mm. Enter diameter, length and quantity to get weight per metre, weight per bar and total weight — useful for ordering steel, estimating freight and checking bar-bending schedules.
Formula
How this is calculated
Steel has a density of approximately 7,850 kg/m³. The cross-sectional area of a circular rebar with diameter d (in mm) is A = π/4 × (d/1000)² m². Multiplying the area by the density gives the weight per linear metre: w = A × 7,850 kg/m. This is equivalent to the industry rule-of-thumb formula w ≈ d²/162 (in kg/m), which is simply the same expression with the constants pre-combined.
For a single bar of length L metres the weight is w × L. For a bundle of n bars the total weight is w × L × n. This figure is used to estimate material orders, calculate freight loads, and set structural design limits. Common rebar sizes range from 6 mm (light slabs) through 32 mm (heavy columns and bridges); the calculator supports custom diameters for non-standard sections.
This calculator assumes solid circular steel bars with a density of 7,850 kg/m³ (the widely used value for structural carbon steel). Deformed rebar has surface ribs that add roughly 3–5% to the weight in practice, but engineering standards still quote nominal weights for the plain circular cross-section — check your local supply specification for the exact value.
Frequently asked questions
A 12 mm diameter rebar weighs approximately 0.888 kg per metre: (π/4) × (0.012)² × 7,850 ≈ 0.888 kg/m. The common approximation formula gives 12² / 162 ≈ 0.889 kg/m.
The formula comes from simplifying the exact physics: (π/4) × (d/1000)² × 7850 = d² × (π × 7850) / (4 × 10⁶) ≈ d² / 162. The constant 162 ≈ 4,000,000 / (π × 7850) is a convenient rounded figure used worldwide for quick estimation.
No. This calculator gives the net weight for the specified number of bars at the specified length. For a real order you should add a wastage factor (typically 3–5%) and account for laps, hooks and bends as required by your structural drawings.
Also known as
TG we-Calculate Editorial Team. (2026). Rebar Calculator — Weight of Reinforcing Steel [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/rebar-calculator
TG we-Calculate Editorial Team. "Rebar Calculator — Weight of Reinforcing Steel." TG we-Calculate. 2026. https://we-calculate.com/calculator/rebar-calculator.
TG we-Calculate Editorial Team, "Rebar Calculator — Weight of Reinforcing Steel," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/rebar-calculator
@misc{wecalculate_rebar_calculator, title = {Rebar Calculator — Weight of Reinforcing Steel}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/rebar-calculator}}, year = {2026}, note = {TG we-Calculate} }
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