Work out rebar weight instantly with clear inputs, formula shown and shareable results.
Reinforcement weight per metre is diameter squared divided by 162, a shortcut that comes from the area of a circle times steel density of 7850 kg/m³. A 12 mm bar therefore weighs 0.888 kg/m and a 16 mm bar 1.58 kg/m, which is how bar bending schedules are priced.
Unit weight
kg/m = d² / 162 (d in mm)
Total
Total kg = d² / 162 x length x number of bars
kg/m = d² / 162 (d in mm). Reinforcement weight per metre is diameter squared divided by 162, a shortcut that comes from the area of a circle times steel density of 7850 kg/m³.
Area in mm² is pi d²/4, and mass per metre is area x 7850 / 10^6. Combining the constants gives d²/162.28, rounded to 162 on site.
This calculator takes 3 inputs: Bar diameter, Length per bar, Number of bars. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.