Project detailsName, client, your steel rate
Only your own figure is used — InstaBOQ adds no rate.
Add every beam, column, slab and footing, enter the section, cover and bars, and get cutting lengths, bar counts and steel weight by diameter. Bend deductions, hooks and development length follow IS 2502 / SP 34 and IS 456. Need it in Excel with formulas? Download the free bar bending schedule Excel template.
Nothing here yet. Add your first member. Each member is one beam, column, slab (and so on) with its bars; if you have six identical beams, add one and set "identical members" to 6.
The example is a beam, a column and a footing.
Assumptions used
- Bend deductions (× bar diameter, per bend)
- 45° = 1d, 90° = 2d, 135° = 3d (SP 34). If you give a bend radius, 45° and 90° bends use the exact geometric deduction 2(r + d)·tan(θ/2) − θ(r + d/2) instead; hooks always use the table.
- 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
- Development length
- Ld = 0.87 fy × d / (4 × 1.6 × τbd), IS 456 Cl 26.2.1, used exactly — not rounded to a whole multiple of d, which can fall short of the code by up to half a diameter.
- 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
- the greater of Ld and 30d (IS 456 Cl 26.2.5.1(c), flexural tension). 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.
- Closer stirrups / ties near the ends
- If you give an end-zone length and spacing, the run is counted as end zone + middle + end zone without counting the boundary bars twice. Zone lengths are never assumed.
- Bent-up (cranked) bars
- two 45° cranks, each adding 0.42 × the centreline offset D' (member depth − 2 × cover − bar diameter), on top of the anchored straight length. Centreline basis, so no extra bend deduction. Not yet hand-verified.
- Continuous beams
- Bottom bars per span: bent down into end supports, Ld/3 past the face at interior supports (IS 456 Cl 26.2.3.3(a)). Top bars continuous, bent down into both end supports, spliced with billed laps when over stock length. Not yet hand-verified.
- Column bars
- Floor height + lap carried up; a crank into the column above adds the slope length at 1 in 6; ground-floor starter bars add the footing depth less cover and an L-foot, with the 90° bend deducted. Circular columns: hoops are π × centreline diameter plus hooks; a helix adds 1.5 turns at each end.
- Lintel, staircase, pile cap
- Lintel bars run opening + bearing each side less cover; the stair is a one-flight waist slab with main bars along the slope (√(run² + rise²)); the pile cap is a plain block with a bottom mat and an optional straight top mat. Step concrete, pile heads and side-face bars are not modelled.
- Steel density ranges (kg/m³)
- beams 100–200, columns 150–280; other members are shown without a verdict — no published range has been checked for them, and a guessed range would be worse than none
A calculation aid, not a design. It applies standard IS conventions to the numbers you enter and does not check that they satisfy any code requirement. A qualified engineer must check and sign off the schedule before any bar is cut.
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, bars bent down into 230 mm supports, M25 / Fe500. These figures are computed by the same code the editor above runs — they are not typed in.
| Bar | Shape | Dia | Cutting length | Total bars | Weight |
|---|---|---|---|---|---|
| Stirrup | Closed rectangle | 8 mm | 1,220 mm | 27 | 13.01 kg |
| Main bar | Bent down both ends | 16 mm | 4,730 mm | 4 | 29.90 kg |
Total steel 42.91 kg over 0.414 m³ of concrete — 103.7 kg/m³.
Bar bending schedule by member
A worked example and the rules for each member type: bar bending schedule for a slab, a beam, a column or a footing.
Frequently asked questions
- What is a bar bending schedule?
- A bar bending schedule 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.