Bar Bending Schedule (BBS) calculator
Work out the cutting length of stirrups/ties or straight bars with hooks, and the total length and steel weight for a given bar count, using standard field-engineering BBS formulas.
Switch between stirrup and straight-bar mode, see the exact formula used at every step, and get the total weight via the same d² ÷ 162.28 unit-weight rule as the Steel/Rebar Weight Calculator. Computed in your browser.
Bar type
Beam/column width.
Beam/column depth.
Stirrup/tie bar size.
Clear cover on each face, default 25 mm.
Total stirrups/ties needed.
Cutting length per bar
1,136 mm
≈ 1.136 m per stirrup
Total weight
22.4 kg
Bar count
50 pcs
Total cutting length
56.80 m
Unit weight
0.394 kg/m
Total weight
22.4 kg
| Cutting-length formula | 2×(A+B) − (8×cover) − (3×diameter) |
| Cutting length | 2×(230+450) − (8×25) − (3×8) = 1,136 mm |
| Total cutting length | 1.136 m × 50 pcs = 56.80 m |
| Unit-weight formula (reused) | w = d² ÷ 162.28 (kg/m) |
| Total weight | 0.394 kg/m × 56.80 m = 22.4 kg |
A simplified, field-standard BBS cutting-length calculation, not a full structural-detailing tool. The stirrup formula assumes a 135° hook (10× diameter) with standard 90° corner and hook bend deductions folded into the 8×cover and 3×diameter terms; the straight-bar formula assumes a 90° hook of 9× diameter at each end and does not account for crank/bent-up bars. Cover and hook assumptions are editable above; always cross-check against your structural drawing and IS 2502 before cutting steel on site.
From member dimensions to a cutting list
Each bar shape has its own standard cutting-length formula; multiplying by the bar count and the unit-weight rule turns that into a total steel requirement.
Cutting length
Stirrups: 2×(A+B) − (8×cover) − (3×diameter). Straight bars: span + 2×(9×diameter) for a 90° hook at each end.
Total length
Cutting length per bar (converted to metres) × the number of stirrups or bars gives the total length of steel needed.
Total weight
Total length × unit weight (d² ÷ 162.28 kg/m), the same rule used by the Steel/Rebar Weight Calculator.
Bar bending schedules, answered
What is a Bar Bending Schedule (BBS)?+
A Bar Bending Schedule is a table listing every reinforcement bar in a structural member, its shape, cutting length, quantity and total weight. It lets a site team order the right amount of steel and cut bars to length before bending, instead of estimating from the structural drawing alone.
What formula does the stirrup/tie mode use, and what does it assume?+
Cutting length = 2×(A+B) − (8×cover) − (3×diameter), where A and B are the beam or column's width and depth, cover is the clear cover on each face (default 25 mm, editable) and diameter is the stirrup bar size. This is the standard simplified field formula: it folds in the perimeter of the tie, deductions for the four 90° corner bends and two 135° hook ends. It assumes a 135° hook (about 10× diameter); it is not a substitute for the exact bend-by-bend calculation on a structural detailing drawing.
What formula does the straight-bar mode use, and what does it assume?+
Cutting length = span + 2×(9×diameter), adding a 90° hook of 9× diameter at each end of the bar to the clear span. This mode is straight-bar only, it does not add or deduct length for crank (bent-up) bars, which are common in beam bottom/top reinforcement and need a separate calculation. Use it for straight main bars, distribution bars and similar members without diagonal bends.
How is the total weight calculated?+
Total cutting length (cutting length per bar × number of bars/stirrups, converted to metres) is multiplied by the standard steel unit-weight rule, weight (kg/m) = diameter² ÷ 162.28, the same formula used by the Steel/Rebar Weight Calculator on this site. The result is the total steel weight in kilograms for that bar mark.
Is this a substitute for a structural detailing drawing?+
No. This is a simplified, field-standard cutting-length calculator matching the formulas commonly used in Nepali site practice (based on IS 2502 conventions), useful for a quick estimate or a sanity check on a supplier's cutting list. It does not handle crank bends, lap lengths, development lengths or complex bar shapes. Always follow the project's approved structural drawings and BBS for actual construction.
Why are the cover and hook length editable?+
Clear cover varies by member type and exposure condition (commonly 20-50 mm per the National Building Code and IS 456), and some engineers specify a 90° hook instead of a 135° hook for stirrups. Editing the cover field lets you match your project's specified cover; for a different hook convention, adjust your own cutting length using the formula shown, since this tool fixes the hook multiplier to the standard values stated above.
Sources & data note
Based on standard field-engineering BBS cutting-length formulas (IS 2502 conventions) used in Nepali site practice, and the same d² ÷ 162.28 unit-weight rule used by the Steel/Rebar Weight Calculator. This is a simplified estimation tool, not a full structural-detailing calculation; verify cover, hook type and bar shapes against your project's approved structural drawings before cutting steel.