Reinforcement calculator
Steel / saria weight calculator
Convert a rebar schedule into kilograms and tonnes using diameter, bar count, length and an editable waste allowance.
Calculation results
How steel weight is calculated
The tool estimates the mass of round steel bar from nominal diameter and length. It does not decide how much reinforcement a structure needs.
Unit weight (kg/m) = diameter² ÷ 162
Total weight = unit weight × total length in metres × (1 + waste %)
Rolling tolerances, couplers, binding wire, laps, hooks and fabrication losses can affect procurement. Compare the estimate with the structural bar-bending schedule.
Worked example
Twenty 12 mm bars, each 40 ft long, equal 243.84 metres. The formula gives about 0.889 kg/m before the selected waste allowance is applied.
From drawing to a checkable steel take-off
Calculate one bar mark at a time. Record the member, diameter, shape, cut length and count before multiplying by unit mass. This makes omissions visible and prevents a single total from hiding whether laps, hooks or starters were included.
For a separate check of the recorded bar and member dimensions, length and dimension tools can help keep the take-off entries consistent.
| Field | Check |
|---|---|
| Bar mark and member | Matches the current structural drawing and bar-bending schedule. |
| Diameter | Nominal millimetres are entered correctly for every group. |
| Cut length | Includes only the bends, hooks and anchorage required by the design. |
| Count | Spacing-derived counts include the correct number of spaces and edge bars. |
| Commercial allowance | Laps, chairs, binding wire, offcuts and stock-length optimization are stated separately. |
The d²/162 shortcut follows from the cross-sectional area of a round bar and an assumed steel density, with unit conversion and rounding. It is a mass conversion, not proof that the delivered steel meets the specified grade, rib geometry or mechanical properties.
Frequently asked questions
What formula is used for rebar weight?
The calculator uses diameter squared divided by 162 to estimate kilograms per metre for round steel bar, then multiplies by total length and waste.
Does this calculator design reinforcement?
No. It only converts a known diameter, count and length into weight. Bar size, spacing, laps and anchorage must come from structural drawings.
Can I enter feet instead of metres?
Yes. Select feet and the calculator converts each bar length to metres before applying the weight formula.
Sources and verification
- ISO 6935-2:2019 — Ribbed bars for concrete reinforcementInternational technical requirements for ribbed reinforcing bars; project specifications may require a different adopted standard.
- Pakistan Standards and Quality Control Authority — Civil standards catalogueOfficial catalogue covering civil materials, including cement and reinforcement standards.
- Pakistan Engineering Council — Building Code of Pakistan 2021National building-code context for safety, administration, structural work and the authority having jurisdiction.
Sources establish the technical context. Calculator planning assumptions remain separately labelled and should be checked for the specific project.
For concrete ingredients around reinforcement, use the concrete and cement calculator.