#28 Ranked Tool · 10,000–25,000 searches/mo

Bar Bending Schedule (BBS) Generator

Generate complete bar bending schedule for RC beams, columns, slabs, and footings. Computes cutting length, bend deductions, weight, and total steel quantity.

Reinforced Concrete Structural engineers, quantity surveyors, site engineers Commercial Intent: VERY HIGH

Engineering Formulas

Cutting Length

Cutting length = Straight length - Bend deductions + Hook additions
90° bend: −2d, 135° bend: −3d, 180° hook: +4d

d: Bar diameter (mm)

Bar Weight

Unit weight (kg/m) = d² / 162
Total weight = unit weight × cutting length × quantity

d: Bar diameter (mm)

Stirrup Cutting Length

A = width − 2×cover, B = depth − 2×cover
Cutting length = 2(A + B) + hook length − bend deductions

A: Inner width (mm)

B: Inner depth (mm)

Development Length

Ld = (φ × σs) / (4 × τbd)
τbd = design bond stress

L_d: Development length (mm)

φ: Bar diameter (mm)

σ_s: Stress in bar (MPa)

τ_bd: Design bond stress (MPa)

Worked Example

Simply Supported Beam BBS

elementType: beamsteelGrade: Fe500concreteGrade: M25barDiameter: 16cover: 25span: 4beamWidth: 0.3beamDepth: 0.5topBars: 3bottomBars: 3stirrupDia: 8stirrupSpacing: 150

Bottom Bars

3 nos × 16 mm φ × 4.0 m = 3 × 4.0 = 12.0 m

Cutting Length

L = 4000 - 2×25 + 2×9×16 = 4000 - 50 + 288 = 4,238 mm

Top Bars

3 nos × 16 mm φ × (4.0/3) = 3 × 1.33 = 4.0 m (curtailed)

Stirrups

8 mm φ @ 150 c/c: n = (4000/150)+1 = 27 nos

Weight

16 mm: 1.58 kg/m × 16.24 m = 25.7 kg, 8 mm: 0.395 kg/m × 27 × 1.6 = 17.1 kg

Result: Total steel: ~42.8 kg for one 4m beam (main bars + stirrups). Approx 110 kg/m³ reinforcement ratio.

Engineering Notes

Cutting length is always less than the straight length due to bend deductions.

For beams, top bars are typically 0.25–0.3× span length for interior spans.

Stirrup spacing must be checked against shear requirements (not just minimum).

Laps should be staggered — no more than 50% bars lapped at any section.

For footings, reinforcement in both directions: bottom reinforcement first, then top.

Assumptions

• No couplers or mechanical splices considered

• Standard hook lengths per IS 2502/BS 8666

• No lapping considered (add separately)

• Weight formula uses density of steel = 7,850 kg/m³

• Clear cover is nominal (design cover may differ)

Common Mistakes

✕ Forgetting bend deductions when computing cutting length

✕ Using outer dimensions instead of centerline for bend calculations

✕ Not accounting for lap length in total steel estimate

✕ Confusing development length with lap length

✕ Using gross length instead of cutting length for weight calculation

Frequently Asked Questions

What is a Bar Bending Schedule?

A BBS is a detailed list of all reinforcement bars in an RC element showing bar mark, diameter, shape, cutting length, quantity, and weight. It is used for fabrication, estimation, and site execution.

What is bend deduction?

Bend deduction accounts for the extra length due to bending. For a 90° bend, deduct 2d; for 135°, deduct 3d. This compensates for the material stretched around the bend.

How is bar weight calculated?

Weight (kg/m) = d²/162, where d is bar diameter in mm. For example, 16 mm bar weighs 16²/162 = 1.58 kg/m.

What is development length?

Development length Ld is the minimum embedment length required to transfer stress from steel to concrete through bond. It depends on bar diameter, steel grade, and concrete grade.

What is clear cover?

Clear cover is the distance from the concrete surface to the nearest reinforcement. Typical covers: beam 25 mm, column 40 mm, slab 20 mm, footing 50 mm (varying by exposure).

What is a standard hook?

A 180° hook with 4d extension (minimum 75 mm) is a standard hook used for anchorage. 90° bend with 12d extension is also common for beam stirrups.

What are the standards for BBS?

IS 2502 (Indian), BS 8666 (British), ACI 315 (American). These specify bar shapes, notation, scheduling formats, and tolerances.

Why is a BBS important?

BBS ensures accurate steel ordering, minimizes wastage, enables prefabrication, aids site supervision, and provides documentation for billing and auditing.