How is cutting length calculated in IS 2502?

Cutting length = sum of straight segment lengths + hook allowances − bend deductions, on a centreline basis. Each bend angle/size has a standard deduction; this is the basis of the bar bending schedule.

Why is a bent bar shorter than its outside dimensions?

Bending follows the bar centreline, which is shorter through the corner than the outside dimensions — hence the standard bend deduction at each bend.

IS 2502:1963 — Code of Practice for Bending and Fixing of Bars fo…

IS 2502:1963 — Clause 3

Cutting Length & Bend Deductions

The cutting (cut) length of a bent bar is not the sum of its outside dimensions: bending follows the centreline, so each bend introduces an allowance/deduction relative to the dimensioned outside lengths. IS 2502 gives the standard bend allowances/deductions (per bend angle and bar size) that underpin every bar bending schedule (BBS) — get them wrong and the bar is cut short or long.

Key Requirements

•Cutting length = Σ straight segment lengths + hook allowances − bend deductions (centreline basis)
•Each 45° / 90° / 135° / 180° bend has a standard deduction/allowance per bar diameter
•Add the standard hook allowance for each end hook (per the hook clause)
•Schedule per the BBS so cutting/bending is reproducible and checkable
•Account for the bar diameter — deductions scale with size; small bars ≠ large bars

Reference Tables

Indicative bend deductions (verify against current edition / BBS practice)

Bend	Indicative deduction (× bar dia)
45° bend	≈ 1 d
90° bend	≈ 2 d
135° bend	≈ 3 d
180° hook	hook allowance ≈ 16 d (incl. extension)

Indicative rule-of-thumb values — use the deductions/allowances of the current BIS edition and the approved BBS for the project.

Formulas

L_cut = Σ L_straight + Σ hook_allowance − Σ bend_deduction

Cutting length of a bent bar (centreline basis)

L_cut = cutting lengthL_straight = dimensioned straight segmenthook_allowance = standard hook additionbend_deduction = standard deduction per bend

Practical Notes

✓BBS errors are overwhelmingly cutting-length / bend-deduction errors — short bars fail laps/anchorage, long bars waste steel and foul formwork.

✓Centreline thinking is the key: a bar bent to a 1 m × 1 m L is shorter than 2 m because the corner follows the inside-of-bend centreline.

Common Mistakes

⚠Summing outside dimensions instead of applying centreline bend deductions (bars cut too long).

⚠Forgetting hook allowances at bar ends (bars effectively short on anchorage).

⚠Using one deduction for all bar sizes (deductions scale with diameter).

Frequently Asked Questions

Related Resources

Cl. hooks.bends Cl. bbs Cl. fixing

View all 4 clauses of IS 2502:1963 →