RCC Column Material Calculator
Calculate concrete volume, steel reinforcement weight, and shuttering area for any RCC column from dimensions, height, IS 456 grade, and reinforcement details.
Reinforcement schedule
How this works
A rectangular column's concrete volume is b × d × H; materials are taken off using the IS 456 dry-volume rule, and steel uses the standard d² / 162.28 kg/m formula:
concreteVol = b × d × H
dryVol = wetVol × 1.54
cementBags = ceil(dryVol × c / parts / 0.0347)
mainBarKg = barCount × H × (barDia² / 162.28)
stirrupCount = ceil(H / spacing) + 1
stirrupKg = stirrupCount × 2(b+d) × (stirrupDia² / 162.28)
steelKg = mainBarKg + stirrupKg
shutterM² = 2(b+d) × HThe simple H × barWeight product ignores lap splices and development lengths into the slab and footing — add roughly 10 percent for procurement.
Worked example
A 3 m tall M20 column, 300 × 300 mm, with 6 × 20 mm main bars and 8 mm ties at 150 mm:
- Concrete =
0.3 × 0.3 × 3 = 0.27 m³ - Main bar weight per metre =
20² / 162.28 ≈ 2.47 kg/m - Main bars =
6 × 3 × 2.47 ≈ 44.4 kg - Tie count =
ceil(3 / 0.15) + 1 = 21 - Tie weight =
21 × 1.2 × 0.395 ≈ 9.95 kg - Steel total ≈ 54 kg
- Shutter =
2 × 0.6 × 3 = 3.6 m²
Sources
- IS 456:2000 §26.5.3 (column ties), §10.3 (dry-volume bulking).
FAQ
What column size should I use for a 2-storey residential house?
For a typical 2-storey RCC residence in non-seismic zones, a 230 × 230 mm column with 4 × 12 mm or 4 × 16 mm main bars is the conventional starting point. For 3 to 4 storeys, 230 × 300 mm with 6 × 16 mm bars is more common. For seismic zones IV and V (or NBC 105 zones in Nepal), the minimum size jumps to 300 × 300 mm and the bar count rises. Always size against a structural drawing rather than this calculator alone.
How are tie spacing and tie diameter chosen?
IS 456 §26.5.3 specifies the minimum tie diameter as 6 mm or one-quarter of the largest main bar diameter, whichever is greater. Tie spacing should be the smallest of: 16 × main bar diameter, 48 × tie diameter, or the least lateral dimension of the column. For a 230 × 230 column with 16 mm main bars, that produces a maximum spacing of about 230 mm — most contractors use 150 mm in practice for a margin of safety.
Why does the steel calculator only multiply by H, not H plus extras?
The simple H × bar weight formula ignores the lap splice (typically 50 × bar diameter at every floor level), the development length into the slab and footing, and the extra reinforcement at column-beam joints. Together those add 8–12 percent to the bar steel quantity. For procurement, multiply the calculator's steel kg by 1.1 as a planning allowance — the precise number comes from the bar bending schedule.
Why is the shutter area 2 × (b + d) × H?
A column shutter wraps all four vertical faces. The two faces of width b each contribute b × H, and the two faces of depth d each contribute d × H — total 2 × (b + d) × H. Top and bottom faces are not shuttered (the slab/footing is poured monolithically). This is the conventional field rule for column formwork procurement.
Can I use the same calculator for circular columns?
No. This calculator assumes a rectangular section. For a circular column of diameter D, the concrete volume is π × (D/2)² × H, the shutter wrap is π × D × H, and the ties become helical hoops with a different developed length. Use a circular-column calculator when your structure is circular, or compute the rectangular equivalent first.
Should I add cover to the dimensions?
No. The b, d, and H you enter should be the gross outer dimensions of the column — what the formwork will produce. Cover (typically 40 mm for columns per IS 456 §26.4) is the distance from the outer face to the centreline of the main reinforcement, and it's already accounted for inside the structural steel design. Don't subtract it from your input dimensions.