# Rebar Cut Length Calculator

Cut length and bar weight with standard hook allowances.

- Page: https://jianzhujisuan.com/en/rebar-cut-length
- Category: Rebar (https://jianzhujisuan.com/en/c/rebar)
- Chinese version: https://jianzhujisuan.com/zh/rebar-cut-length.md
- Data checked: 2026-10-25

## Quick result

With the default inputs (Member clear length 6000 mm, Concrete cover 25 mm, Bar diameter 20 mm, End hooks 180° hook, Number of bars 100 pcs): **Cut length 6200 mm**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Member clear length | number | 6000 | mm |  |
| Concrete cover | number | 25 | mm |  |
| Bar diameter | number | 20 | mm |  |
| End hooks | select | 180° hook | — |  |
| Number of bars | number | 100 | pcs |  |

## 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

## Worked example

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.

## Questions

### 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.

## Related tools

- [Rebar Weight Calculator](https://jianzhujisuan.com/en/rebar-weight): Pick a bar diameter, enter length and quantity to get weight per metre, per bar and total tonnage.
- [Rebar Anchorage Length Calculator](https://jianzhujisuan.com/en/rebar-anchorage): Basic and seismic anchorage length from bar grade, diameter and concrete class.
- [Rebar Lap Length Calculator](https://jianzhujisuan.com/en/rebar-lap): Lap length ll / llE by splice percentage, plus the permitted number of splices.
- [Rebar Spacing and Bar Count Calculator](https://jianzhujisuan.com/en/rebar-spacing): Bars and actual spacing from run length and design spacing, with total weight.
- [Stirrup Length and Count Calculator](https://jianzhujisuan.com/en/rebar-stirrup): Stirrup length, count and weight with the 11.9d seismic hook allowance.
- [Rebar Mesh Weight Calculator](https://jianzhujisuan.com/en/rebar-mesh): Weight per square metre and total mesh weight from dimensions and spacings.

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Generated by BuildCalc. All calculations run in your browser; no data is uploaded. Formulas follow national standards and common trade practice; local codes govern.