How is cutting length different from the member dimension?

A bar is measured along its centre after bending, but it is set out from the member's dimensions minus cover. Bending a bar round a corner makes the bent bar shorter than the sum of its outside legs, so a deduction is applied at every bend, and hooks are added at the ends. Cutting length is the straight length to cut before any of that bending happens.

Why subtract a bend deduction?

Measuring a bent bar along its outside faces counts the corner material twice. IS 2502 / SP 34 give a standard deduction per bend as a multiple of bar diameter — 2d at a 90° bend and 3d at a 135° bend — which converts the outside measurement into the real length of steel needed.

How many bends does a closed rectangular stirrup have?

Five. Three 90° corners plus one hook at each end. A common mistake is to count only three, which under-deducts and over-orders steel on every stirrup in the job.

Why is there a 75mm minimum hook length?

IS 13920, the ductile detailing code, sets a floor on the 135° hook so the hook still engages the core after bending. On small bars the 10d figure falls below it — for an 8mm bar 10d is 80mm and clears the floor, but a 6mm bar's 60mm does not and is raised to 75mm.

What is development length, and why does it depend on concrete grade?

Development length is how far a bar must extend past the point it is fully stressed for the bond between steel and concrete to carry that force. Stronger concrete bonds better, so it needs less length. This calculator derives it from IS 456 Cl 26.2.1 rather than a memorised table.

Why does the calculator refuse to guess a 6-leg tie arrangement?

A leg count alone does not describe a tie set. Six legs can be built as a closed rectangle plus two cross ties, or as overlapping rectangles, and those use different amounts of steel. Rather than pick one silently, the calculator says so and asks you to read the arrangement off the section on your drawing.

Are these results safe to build from?

No. This is a calculation aid, not a design. It applies standard IS conventions to the numbers you type; it does not check that those numbers satisfy any code requirement, and it does not design reinforcement. A qualified engineer must sign off the schedule before anything is cut.

Bar Bending Schedule Calculator

Enter a member's section, cover and reinforcement to get cutting lengths, bar counts and steel weight — for a beam, column, slab or isolated footing. Bend deductions, hooks and development length follow IS 2502 / SP 34 and IS 456. Free, no login, nothing stored.

Clear cover (mm)

Concrete grade

Steel grade

Number of identical members

Beam width b (mm)

Beam overall depth D (mm)

Clear span, face to face of supports (mm)

Main bar diameter

Number of main bars

Stirrup diameter

Stirrup spacing c/c (mm)

Hook angle

Clear cover (mm)

Concrete grade

Steel grade

Number of identical members

Clear length between supports (mm)

Clear width between supports (mm)

Slab thickness (mm)

Support width (mm) — optional. Used for gross concrete volume.

Main bar diameter

Main bar spacing c/c (mm)

Distribution bar diameter

Distribution bar spacing c/c (mm)

End anchorage

Bent-up leg length (mm)

Include top bars over supports

Top bar diameter

Top bar spacing c/c (mm)

Top bar extent from support face (mm)

Top bar direction

Beta. Results follow IS-standard conventions — stirrup and tie dimensions taken outside-to-outside (member size minus twice the cover), 10d hooks with the IS 13920 75mm floor, and standard IS 2502 bend deductions. Check them against your own working before cutting steel, and tell us if a number disagrees with yours.

Assumptions used

Bend deductions (× bar diameter, per bend): 45° = 1d, 90° = 2d, 135° = 3d
Hook length (× bar diameter): 90° = 12d, 135° = 10d
Minimum hook length (IS 13920): 75mm floor, applied to the 135° hook only
Unit weight (IS 1786): d² / 162 kg per metre
Cutting lengths: rounded half-up to the nearest 10mm, once
Tie leg arrangements resolved: 2 legs = 1 × closed_rect; 3 legs = 1 × closed_rect, 1 × single_leg; 4 legs = 1 × closed_rect, 2 × single_leg
Stock length for splicing: 12000mm. A bar longer than this is split into stock-length pieces and the lap steel at each splice is ADDED to the total length and weight — so for a spliced bar, total length is more than cutting length × bar count, by design.
Splice lap length: derived from IS 456 Cl 26.2.1 for the chosen grades (the same basis as development length), not a 50d rule of thumb. If a grade pair has no tabulated bond stress, a bar needing a splice is reported as uncomputable rather than spliced with a zero lap.
Steel density ranges (kg/m³): beams 100–200, columns 150–280; slabs and footings have no published range in this engine, so no verdict is given

What is a bar bending schedule?

A bar bending schedule lists every reinforcement bar in a concrete member — its shape, diameter, cutting length, how many are needed, and what they weigh. The fabricator cuts and bends from it; the estimator orders steel from it. Getting the cutting length right matters because a bar bent round a corner is shorter than the sum of its outside legs, so a deduction applies at every bend and a hook is added at each end.

Worked example — 230 × 450 mm beam

A 230 × 450 mm beam spanning 4000 mm clear, with 4 × 16 mm main bars and 8 mm stirrups at 150 mm c/c, 25 mm cover, M25 / Fe500. These figures are computed by the same code the calculator above runs — they are not typed in.

Bar	Shape	Dia	Cutting length	Total bars	Weight
Stirrup	Closed rectangle	8 mm	1220 mm	27	13.01 kg
Main bar	Straight	16 mm	5570 mm	4	35.21 kg

Total steel 48.22 kg over 0.414 m³ of concrete — 116.5 kg/m³.

Frequently asked questions

What is a bar bending schedule?: A bar bending schedule (BBS) is a tabulated list of every reinforcement bar in a concrete member: its shape, diameter, cutting length, number of bars, and total weight. Fabricators cut and bend from it, and quantity surveyors order steel from it, so it sits between the structural drawing and the site.
How is cutting length different from the member dimension?: A bar is measured along its centre after bending, but it is set out from the member's dimensions minus cover. Bending a bar round a corner makes the bent bar shorter than the sum of its outside legs, so a deduction is applied at every bend, and hooks are added at the ends. Cutting length is the straight length to cut before any of that bending happens.
Why subtract a bend deduction?: Measuring a bent bar along its outside faces counts the corner material twice. IS 2502 / SP 34 give a standard deduction per bend as a multiple of bar diameter — 2d at a 90° bend and 3d at a 135° bend — which converts the outside measurement into the real length of steel needed.
How many bends does a closed rectangular stirrup have?: Five. Three 90° corners plus one hook at each end. A common mistake is to count only three, which under-deducts and over-orders steel on every stirrup in the job.
Why is there a 75mm minimum hook length?: IS 13920, the ductile detailing code, sets a floor on the 135° hook so the hook still engages the core after bending. On small bars the 10d figure falls below it — for an 8mm bar 10d is 80mm and clears the floor, but a 6mm bar's 60mm does not and is raised to 75mm.
What is development length, and why does it depend on concrete grade?: Development length is how far a bar must extend past the point it is fully stressed for the bond between steel and concrete to carry that force. Stronger concrete bonds better, so it needs less length. This calculator derives it from IS 456 Cl 26.2.1 rather than a memorised table.
Why does the calculator refuse to guess a 6-leg tie arrangement?: A leg count alone does not describe a tie set. Six legs can be built as a closed rectangle plus two cross ties, or as overlapping rectangles, and those use different amounts of steel. Rather than pick one silently, the calculator says so and asks you to read the arrangement off the section on your drawing.
Are these results safe to build from?: No. This is a calculation aid, not a design. It applies standard IS conventions to the numbers you type; it does not check that those numbers satisfy any code requirement, and it does not design reinforcement. A qualified engineer must sign off the schedule before anything is cut.