Civil Engineering · Reinforcement
Rebar Weight & Quantity
Reinforcement bar weight from diameter, length and count — computed from steel density, with the familiar site rule of thumb (d²/162) shown for cross-reference.
Standard method — stated scope limits apply
Bar
Enter bar diameter, length and count.
About This Calculation
Reinforcement bar weight comes directly from geometry and steel density — the cross-sectional area of a round bar times its length times the density of steel. This calculator computes that precisely rather than relying on the rounded rule of thumb (d²/162 kg/m) that’s widely used on site, though the two agree closely: the difference is under 0.2% for any standard bar size, which is exactly why the rule of thumb has stuck around — it’s a very good approximation, just not an exact one.
Frequently Asked Questions
Why does the calculator show both a precise value and the d²/162 rule of thumb?
So you can cross-check against the number a site engineer would calculate by hand or recognize from memory — the two should always agree closely; a large mismatch would indicate a data-entry error rather than a real discrepancy in the physics.
What steel density does this use?
7850 kg/m³, the standard value for structural and reinforcing steel used in virtually all rebar weight tables and mill certificates.
Does bar length here mean the cut length or the finished length after bends and hooks?
Enter the actual cut length of the bar, including any allowance for hooks or bends — the calculator has no way to know your bar bending schedule, so the length you provide should already reflect the real fabricated length.
How do I estimate total reinforcement weight for a whole structural element?
Calculate the weight per bar here, then multiply by the number of bars of that diameter and length — the "number of bars" field does exactly this multiplication for you, useful once you have a bar bending schedule with bar counts by diameter.