Beam Bar Bending Schedule Calculator | Free BBS course

Beam Bar Bending Schedule (BBS) Calculator

Input Details

Clear Span of Beam (mm)

Beam Width (mm)

Beam Depth (mm)

Clear Cover (mm)

Main Bar Diameter (mm)

Number of Top Bars

Number of Bottom Bars

Development Length Factor (Ld × d)

Stirrup Diameter (mm)

Stirrup Spacing c/c (mm)

Hook Type 90° Hook (10d) 135° Hook (12d)

Number of 90° Bends in Stirrup

Number of 135° Hook Bends in Stirrup

Calculation Results

Important Notes & Assumptions

• Main bar cutting length includes both development lengths.
• Development Length Formula: Ld = Development Length Factor × Bar Diameter
• Standard bend deductions used:
• 90° bend deduction = 2d
• 135° bend deduction = 3d
• Steel unit weight formula: d² / 162 kg/m
• Number of stirrups formula: (Beam Length ÷ Spacing) + 1
• This calculator is intended only for preliminary estimation. Always verify manually before execution on site.

Detailed Explanation of BBS Terms

Term	Explanation
Clear Span	Distance between inner faces of supports.
Development Length (Ld)	Extra reinforcement length provided for proper anchorage.
Main Bars	Primary longitudinal reinforcement in the beam.
Stirrups	Transverse reinforcement resisting shear force.
Clear Cover	Concrete thickness protecting reinforcement from corrosion.
Hook Length	90° Hook = 10d 135° Hook = 12d
Bend Deduction	90° Bend = 2d 135° Bend = 3d
Steel Unit Weight	d² / 162 kg/m
Stirrup Spacing	Center-to-center distance between stirrups.

Engineering Recommendations

• Recommended clear cover:
  • 20 mm for mild exposure
  • 25–40 mm for moderate/severe exposure
• 135° hooks are preferred for seismic detailing.
• Verify development length as per IS 456.
• Provide closer stirrup spacing near supports.
• Check the following before finalizing BBS:
  • Lap lengths
  • Curtailment lengths
  • Anchorage details
  • Concrete cover blocks

Designed & Developed by Mohan Dangi (Gold Medalist)