Rebar Weight and Quantity Calculator

How is rebar weight calculated?

The weight of one metre of reinforcing bar is its cross section multiplied by the density of steel: m = π / 4 × d² × 7850, where d is the diameter in metres and 7850 kg/m³ is the density of steel. Total weight is mass per metre times length times quantity.

The site shortcut d² / 162 (d in millimetres) is the same formula rounded, and it reads about 0.1 percent high. This calculator uses the unrounded formula.

Example

For 10 bars of 12 mm diameter and 6 m length: mass per metre is π / 4 × 0.012² × 7850 = 0.888 kg/m, total length 60 m, weight 60 × 0.888 = 53.3 kg.

Mass per metre

Nominal masses from the standard table for common sizes: 8 mm 0.395 kg/m, 10 mm 0.617 kg/m, 12 mm 0.888 kg/m, 14 mm 1.21 kg/m, 16 mm 1.58 kg/m, 20 mm 2.47 kg/m. The table below the calculator lists every size.

How to use it

Add one row per bar mark: choose the diameter, then enter the cutting length and the quantity. The calculator gives the weight of each row, totals by diameter and the grand total in kilograms and tonnes. With a waste allowance it also shows the order weight and the number of 12 metre stock bars. The list can be downloaded as CSV and opened in a spreadsheet.

Limits

This is a quantity and ordering tool, not a reinforcement design tool. Hook and lap lengths must be included in the cutting length by you. The bar count is not a cutting plan. Delivered weight may differ slightly from the calculated value because of rolling tolerances.