Rebar Cut Length Calculator
Cut length and bar weight with standard hook allowances.
Inputs
Result
Formula
| Clear length | L = member length − 2 × cover |
| Hook allowance | k × d (6.25 at 180°, 4.9 at 135°, 3.5 at 90°) |
| Cut length | L_cut = L + 2 × allowance |
| Weight per bar | W = 0.00617 × d² × L_cut ÷ 1000 kg |
A 6000 mm bar with 25 mm cover and 180° hooks at 20 mm: 5950 mm clear plus 125 mm per end gives a 6200 mm cut, 15.30 kg per bar and 1530 kg for 100 bars.
FAQ
Why is cut length not the drawing dimension?
Drawings give external dimensions measured to the outside face, but bending stretches the outside and compresses the inside — the centreline length is what you must cut. So sum the external segments and deduct a bend allowance at each bend, adding hook allowances at the ends. Getting this wrong scraps the whole batch.
Why is a 180° hook 6.25d?
The developed length is the half-circle (π × 2.5d ÷ 2 ≈ 3.93d) plus the straight tail, adjusted for bend elongation — 6.25d is the field value. Code editions differ slightly (some give 6.25d, others compute from a 2.5d bend diameter), so follow the standard your project cites.
How is a stirrup cut length calculated?
Stirrups use the external perimeter plus hook allowances, not 2 × 6.25d. Seismic stirrups have 135° hooks at 11.9d each, covering a 10d tail and the bend increment: length = 2(b − 2c) + 2(h − 2c) + 2 × 11.9d. There is a dedicated stirrup calculator on this site.
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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.