Free online weight calculator for rebar
Accurate rebar quantities are essential for any concrete project. Small domestic jobs can tolerate rough estimates, but larger slabs, beams and foundations rely on precise steel weights to avoid delays, overspending and material shortages. This calculator helps you work out exact rebar weights for every diameter and shape in your schedule, using industry standard bar masses.
BS CODE 00
Total Length (L)
(L)= A(L)= A
BS CODE 21
Total Length (L)
(L)= A + B + (C) – r – 2d
BS CODE 11
Total Length (L)
(L)= A + (B) – 0.5r — d
BS CODE 51
Total Length (L)
(L)= 2(A + B + (C)) – 2.5r – 5d
Rebar Weight Calculations
| Crt. No |
Rebar Diameter | Length (Millimetres) | Quantity | Weight | Shape Code |
|---|
| Crt. No |
Rebar Diameter | Length (Millimetres) | Quantity | Weight | Shape Code |
|---|
| Crt. No |
Rebar Diameter | Length (Millimetres) | Quantity | Weight | Shape Code |
|---|
This calculator uses mass per metre values taken from BS 8666 and applies standard bending allowances for each Shape Code. The totals you see match typical weighbridge values for cut and bent reinforcement.
Why Accurate Rebar Weights Matter
Different bar diameters have different unit weights, and even small errors can compound across a project. If your estimates are too low, you risk shortages and delivery delays. If they are too high, you pay for steel you do not need. This tool removes guesswork and gives you reliable totals that can be used for ordering and for weighbridge checks on delivery.
How to use our rebar weight calculator
Choose your bar diameter
Select the bar size from the dropdown. Each diameter uses the correct weight per metre, so the calculation remains accurate.Set the bar length
Adjust the length field for each item. The calculator updates automatically as you change it.Enter the quantity
Add the number of bars needed for that diameter and length combination.Select a Shape Code
Use the Shape Code dropdown to assign your required form. If you need to check a code, click the See List button above the field. The calculator applies the appropriate bending allowances where required.Add more lines as needed
Use the plus button to generate additional rows for other diameters, lengths or shapes. The combined weight updates in real time at the bottom of the tool.
When you are finished, choose one of the output options.
Download PDF for site files or quantity records
Print for quick reference
Contact Us to have your entries sent directly to our team for a formal quotation
Benefits of using a rebar weight calculator
Accurate weight calculations specific to the diameter and length you select
Reduced wastage and fewer delays from under ordering
Clear totals that match weighbridge delivery checks
Better planning for transport, cranage or manual handling
Easy project documentation via PDF or print export
If you need help choosing bar diameters, Shape Codes or reinforcement layouts, contact our team. We can provide guidance, estimates and full reinforcement packages for projects of any size.
Definition List
T10, T12, T16
Common UK reinforcement bar diameters measured in millimetres. For example, T12 refers to a 12 mm bar.
Shape Code
A standardised reference that defines the bar’s geometry. Shape Codes follow BS 8666 and specify bending dimensions and radius requirements. You can view the full list on our Shape Code Chart.
Mass per metre
The theoretical weight of a reinforcement bar per metre of length. Each diameter has a fixed mass per metre. The calculator uses these values to generate accurate totals.
Straight bar
A bar with no bending requirements. Usually listed as Shape Code 00.
Bending allowance
The extra length needed to form bends in shaped bars. This allowance is included automatically when you select a Shape Code.
Disclaimer
This tool is for estimating rebar weights only. It does not replace structural design calculations or engineering specifications. Always follow your engineer’s drawings and reinforcement schedules.
