Rebar Weight & Quantity Calculator
Use bar diameter, required length and an allowance for laps/cuts to estimate steel weight and stock bars.
Estimate rebar weight and stock-bar quantity
Use bar diameter, required length and an allowance for laps/cuts to estimate steel weight and stock bars.
How the rebar weight & quantity calculator works
For metric reinforcing bar, a common estimating approximation for unit mass is diameter² ÷ 162 kg/m. The calculator applies the entered lap/cut allowance to total length, then multiplies by unit mass and rounds stock bars up by stock length.
Where this construction calculation helps
Use it for preliminary reinforcement takeoffs and weight cross-checks when bar diameter and total scheduled length are known.
Measurements and assumptions
The d²/162 relationship is an approximation. Actual certified unit mass, rib geometry and project standards may differ slightly. A true bar-bending schedule must account for bends, hooks, lap lengths, couplers, bar marks and cutting optimization.
Worked example
A 12 mm bar has an estimated unit weight of about 0.889 kg/m. Five hundred metres plus a 5% allowance weighs about 467 kg.
Convert reinforcement length into purchasing weight
A rebar weight calculator uses bar diameter and total length to estimate steel mass. It is useful for takeoffs, procurement checks and comparing reinforcement schedules, but total bar length should include the detailing shown on approved drawings. Laps, hooks, bends, anchorage, starter bars and cutting waste can add substantial length beyond simple member dimensions. Bar unit weight can also vary slightly by standard and manufacturing tolerance. Use the calculated weight as an estimating check and rely on the structural bar bending schedule for final reinforcement quantities.