CONCRETE
Concrete Calculator: Volume, Cement Bags, Sand & Aggregate
Calculate concrete volume for a slab, beam, footing or column, with cement bags, sand and aggregate for M10, M15 and M20 nominal mixes.
Assumptions used EDIT ▾
Commonly 1.52–1.57.
Wet volume = length × width × depth (or π r² h). Dry volume = wet volume × the dry factor, because the dry ingredients shrink when mixed with water. Materials are split in the chosen ratio; cement is converted at 1,440 kg/m³ and 50 kg per bag. Nominal-mix quantities are an estimating convention; a design mix will specify its own proportions.
CONCRETE VOLUME
1.46m³
52 cft · includes 3% extra. Order about 1.5 m³ of ready-mix.
- Cement11.8 × 50 kg
- 12 bags
- Sand0.61 m³
- 22 cft
- Aggregate (20 mm)1.22 m³
- 43 cft
- Before wastage
- 1.42 m³
How it’s calculated
Dry volume = wet volume × 1.54; cement = dry × 1 ÷ (1 + sand + aggregate) × 1440 ÷ 50 bags
Example: 1 m³ of M20 (1:1.5:3): dry 1.54 m³ → cement 0.28 m³ ≈ 8.1 bags.
Questions
Why multiply by 1.54?+
Dry cement, sand and aggregate shrink in volume once water is added and the concrete is compacted. 1.52–1.57 is the usual allowance.
Can I use nominal mix for M25?+
Nominal mixes are used up to M20. For M25 and above use a design mix.
Estimates for planning, based on the assumptions shown. They are not a guarantee of quantities or professional engineering advice; check critical work with a qualified professional.