Rebar Weight Calculator

Work out rebar weight instantly with clear inputs, formula shown and shareable results.

About Rebar Weight Calculator

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.

Formulas

Unit weight

kg/m = d² / 162 (d in mm)

Total

Total kg = d² / 162 x length x number of bars

Worked example

With the default values below, Rebar Weight Calculator returns Total steel weight of 533.33. Change any input above and every figure here is recalculated in your browser.

Inputs used

Bar diameterminimum 4 mm: 12 mm
Length per barminimum 0.1 m: 12 m
Number of barsminimum 1: 50

Results

Total steel weight: 533.33 kg
Weight per metre: 0.8889 kg/m
Weight per bar: 10.667 kg
Total weight in tonnes: 0.5333 t

Step by step

1Values used
2Unit weight
3Total
4Total steel weight= 533.33 kg
5Weight per metre= 0.8889 kg/m
6Weight per bar= 10.667 kg
7Total weight in tonnes= 0.5333 t

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Rebar Weight figure worked out?

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.

Where does 162 come from?

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.

What values do I need to enter?

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.