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Rebar Cut Length Calculator

Cut length and bar weight with standard hook allowances.

Quick answer

With the default inputs: Member clear length 6000 · Concrete cover 25 · Bar diameter 20 etc.Cut length 6200 mm

Edit the inputs below to recalculate.
Length LΦ d
Cut length = clear span − cover + hooks + laps − bend allowance.

Inputs

pcs

Result

Cut length
6200mm
After deducting cover5950mm
Hook allowance per end125.0mm
Hook factor6.25d
Cut length in metres6.200m
Weight per bar15.30kg
Total length620.0m
Total weight1530.2kg

Hook allowances are the common values (6.25d at 180°, 4.9d at 135°, 3.5d at 90°) and already include the bend deduction. For multi-bend or bent-up bars, sum the external dimensions and deduct each bend separately rather than using this formula.

Formula

Clear lengthL = member length − 2 × cover
Hook allowancek × d (6.25 at 180°, 4.9 at 135°, 3.5 at 90°)
Cut lengthL_cut = L + 2 × allowance
Weight per barW = 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.

How to work it out

  1. Read the dimensioned sizes and establish whether they are outside-to-outside or centreline.
  2. Deduct the bend allowance for each bend: 0.35d at 30°, 0.5d at 45°, 0.85d at 60°, 2d at 90°, 2.5d at 135°.
  3. Add hook allowances: 6.25d for a 180° semicircular hook, and for 135° stirrup hooks the greater of 10d straight and 75 mm.
  4. Cutting length = sum of outside dimensions − bend deductions + hook allowances.
  5. Optimise against stock length: group the same size together to minimise offcuts.

Where it goes wrong

Material and cost

A cutting error costs rework, not material: 50 mm short on a 25 mm bar scraps a 300-bar batch, about 15,000 at 4000 per tonne, before you count the delay. Good stock optimisation, on the other hand, saves 3-5% of steel — 150,000-250,000 on a 5,000 tonne job.

On site

Basis

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.

Cite this page

Use this format in reports, method statements or coursework. The link is permanent.

Building Calculator. Rebar Cut Length Calculator. 2026-10-25. https://jianzhujisuan.com/en/rebar-cut-length

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.