Concrete & Cement Calculator
Estimate cement bags, sand and crush (gravel) for a slab, footing, beam or column.
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About the Concrete & Cement Calculator
Enter the size of a slab, footing, beam or column to estimate the volume of concrete and the dry materials needed for the mix you choose.
Common mixes are 1 : 1.5 : 3 (about M20, for slabs, beams and columns), 1 : 2 : 4 (M15, general work and floors), 1 : 3 : 6 (M10, foundations / PCC) and 1 : 4 : 8 (lean concrete). Use Number of identical pieces for several equal columns or footings.
How to use the Concrete & Cement Calculator
- Choose feet or metres.
- Enter length, width and thickness (inches when using feet, centimetres when using metres).
- Pick the mix ratio and the number of identical pieces.
- Click Calculate materials.
Formula
Wet volume = length × width × thickness × pieces.
Dry volume = wet volume × 1.54 (allows for voids and shrinkage).
Each material = dry volume × its parts ÷ total parts. For 1 : 2 : 4 the total is 7 parts.
Cement bags = cement volume ÷ 0.0347 m³ (one 50 kg bag ≈ 1.25 cft).
Examples
- A slab 10 × 10 ft, 5 inches thick, mix 1 : 2 : 4 → 41.67 cft (1.18 m³) of concrete → 7.5 bags of cement, 18.3 cft sand and 36.7 cft crush.
- Four column footings of 4 × 4 ft × 12 in: set pieces to 4.
Frequently asked questions
How accurate is this estimate?
It is a planning estimate based on standard formulas. Actual quantities depend on workmanship, material quality and site conditions, so confirm with your contractor or engineer before buying.
Does this include steel (sariya)?
No. Steel depends on the structural design. Ask your engineer for the steel schedule.
Why multiply by 1.54?
Dry materials fill less space once mixed with water, and some is lost. 1.52 to 1.57 is the usual allowance; 1.54 is a common middle value.