Steel Quantity in Columns: 2-Minute BBS Guide with Formulas & Tables

How to Calculate Steel Quantity in a Column (BBS Guide)

Calculating the quantity of steel in a column (Bar Bending Schedule - BBS) is essential for civil engineering projects. This guide simplifies the process using a practical example.

Example Scenario

• Column Specs: Height = 3 m, Cross-section = 500 x 400 mm
• Vertical Bars: 6 nos., Diameter = 16 mm
• Stirrups: Diameter = 8 mm, Spacing = 150 mm and 200 mm at L/3 respectively
• Clear Cover: 40 mm (large columns)

Tool Tip: Use our for faster concrete quantity estimation.

Step-by-Step Calculation

Step 1: Longitudinal Bars Calculation

• Formula: Length of 1 Rod = Height (H) + Development Length (Ld)
• H = 3000 mm
• Ld = 50d (d = diameter of bar)
• Length of 1 Rod:
• = 3000 + 50(16)
• = 3000 + 800
• = 3800 mm or 3.8 m
• Total Length:
• 6 bars x 3.8 m = 22.8 m of 16 mm bar

Step 2: Cutting Length of Rectangular Stirrups

Dimensions After Clear Cover

Side	Original (mm)	Clear Cover (mm)	Adjusted (mm)
A	500	2 x 40	420
B	400	2 x 40	320

Number of Stirrups

• Zones: L/3 = 3000/3 = 1000 mm
• Top Zone: 1000 / 150 = 7 nos
• Bottom Zone: 1000 / 150 = 7 nos
• Mid Zone: 1000 / 200 = 5 nos
• Total Stirrups: 7 + 5 + 7 + 1 = 20 nos

Cutting Length of One Stirrup

• Formula: Cutting Length = 2(a + b) + 2(9d) – 3(2d) – 2(3d)
• a = 420 mm, b = 320 mm, d = 8 mm
• Calculation:
• = 2(500 + 400) + 2(9x8) – 3(2x8) – 2(3x8)
• = 1800 + 144 – 48 – 48
• = 1848 mm or 1.84 m
• Total Length: 20 x 1.84 = 36.8 m of 8 mm bar

Final Steel Quantity

Component	Quantity	Diameter
Longitudinal Bars	22.8 m	16 mm
Rectangular Stirrups	36.8 m	8 mm

Note: For steel weight, use formula D²/162 for 1 m. Learn more .

Dive Deeper

Want detailed formulas and tips? Check out the for more on BBS and steelquantity estimation in civil engineering.

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