Rebar Weight & Length Calculator
Calculate the total weight and length of reinforcing bar (rebar) for concrete structures based on bar diameter, count, and lap splice allowances.
Results
What is it?
This calculator determines the total weight and length of steel reinforcing bars needed for a concrete element. Rebar weight is calculated using the standard formula: weight (kg/m) = (diameter² / 162.28) for metric bars, or from published section tables. Lap splices add extra length at bar joints and are typically 40–60 × bar diameter, expressed as a percentage of bar length.
How to use
Select the bar diameter from standard sizes. Enter the design length of each bar and the total quantity. Add a lap splice percentage if bars need to be joined — 10% is a common starting allowance for estimating.
Example scenario
A retaining wall requires 40 bars of 16 mm diameter, each 4 m long, with 10% lap splice allowance. Total length = 40 × 4 × 1.10 = 176 m. Total weight = 176 × 1.578 = 277.7 kg.
Pro tip
Unit weight of rebar = (d² / 162.28) kg/m where d is diameter in mm. Always add 5–15% wastage for cutting and bending. For large projects, work in tonnes to get a direct comparison with supplier quotes.