Rebar weight calculator
Enter the bar diameter in millimetres, its length and the number of bars to get the total weight of your steel order.
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How to use it
- Enter bar diameter, bar length and number of bars.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Weight per metre = π ÷ 4 × diameter² × 7850 ÷ 1,000,000 (diameter in mm, steel at 7850 kg/m³), close to diameter² ÷ 162. Total = kg/m × length × count.
Example
Inputs: Bar diameter = 12 mm, Bar length = 12 m, Number of bars = 10. Result: Total weight: 106.54 kg; Weight per metre: 0.888 kg/m; Total length: 120 m.
Limits and caveats
- Uses nominal mass at 7850 kg/m³; standards allow a small tolerance on actual mass.
- Lap lengths and hooks are not added, so include them in the length.
Questions about this tool
How much does a 12 mm bar 12 m long weigh?
It is 0.888 kg per metre, so the full bar weighs about 10.65 kg.
Is the diameter² ÷ 162 rule right?
It is a common shortcut for the exact π ÷ 4 × d² × 0.00785, and the gap is under 0.1%.
How many 16 mm bars are in a tonne?
A 12 m bar of 16 mm weighs about 18.94 kg, so a tonne holds roughly 52.8 bars.