Rebar weight calculator.
Calculate reinforcement bar weight from diameter, length and quantity. Enter the cut length, diameter and quantity for each bar mark, & this rebar weight calculator will find the total weight plus the combined total, with your lap and waste allowance added on top. Weight per bar comes from a standard round-bar mass formula, so it holds for any diameter, not just common stock sizes. This calculator is for ordering and costing steel, not a substitute for a bar bending schedule from a structural engineer. Use our Concrete Volume Calculator if you need the pour volume this steel goes into.
Drop an Excel or CSV file or to replace the table below.
Column A: bar mark. Column B: cut length. Columns C and D (optional): diameter in mm and quantity — rows without a recognised diameter default to 16 mm, quantity defaults to 1.
Parsed entirely in your browser — your file is never uploaded to our servers.
| Bar mark | Cut length (m) | Diameter | Quantity | Weight (kg) | Row actions |
|---|---|---|---|---|---|
| — | |||||
| — | |||||
| — |
How we calculate this.
Calculate reinforcement bar weight from diameter, length and quantity. Enter the cut length, diameter and quantity for each bar mark, & this rebar weight calculator will find the total weight plus the combined total, with your lap and waste allowance added on top. Weight per bar comes from a standard round-bar mass formula, so it holds for any diameter, not just common stock sizes. This calculator is for ordering and costing steel, not a substitute for a bar bending schedule from a structural engineer. Use our Concrete Volume Calculator if you need the pour volume this steel goes into.
For each bar mark (row): weight = quantity × cut length × unit weight, where unit weight (kg/m) = 0.00617 × diameter² (mm). The total across every row is summed, then a shared lap/waste allowance is added on top for the ordering total.
| Assumption | Value | Source |
|---|---|---|
| Unit weight formula | 0.00617 × diameter² kg/m | Derived from steel density 7,850 kg/m³ and a solid circular cross-section — the same coefficient published (as the ≈ d²/162 approximation) across steel reinforcement reference tables, e.g. BS 4449 / ASTM A615 nominal mass conventions. |
| Lap / waste allowance | 5–10%, default 5% | Typical allowance for lap lengths, chairs/spacers and cutting waste on a reinforcement takeoff — general estimating practice, confirm against your own bar bending schedule. |
This is an early-appraisal planning estimate, not a quotation or a substitute for a surveyed takeoff. Last reviewed 5 Aug 2026.
From a standard formula, not a lookup table: weight per metre (kg/m) = 0.00617 × diameter² in mm — derived from steel's density and a solid round cross-section. Multiply by cut length and quantity for a bar mark's total weight.
A bar bending schedule's cut lengths rarely account for every lap, chair or offcut. Adding a lap/waste percentage on top of the raw calculated weight gives a more realistic ordering figure.
Yes — the weight formula is calculated from the diameter you select, not read from a fixed table, so it holds for every standard size listed.
No. This estimates total steel weight for ordering and costing — the actual bar bending schedule, with bend shapes and exact lap positions, still needs a qualified engineer or detailer.
Yes — click or drop an Excel (.xlsx/.xls) or CSV file onto the upload area. The first column should be an item name and the second the measurement for that row; extra columns this calculator uses are read too if present. The file is parsed entirely in your browser — it's never uploaded to our servers. Download the blank template first if you're not sure of the layout.
Yes — use the metric/imperial switch above the calculator. Values you've already entered convert automatically; nothing is lost switching back and forth.
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