Cement Calculator
Enter your pour size and concrete grade to get the number of 50 kg cement bags — and an optional cost estimate from your bag price.
How the cement calculator works
Cement is a fixed share of the concrete mix. We take the dry volume (wet volume × 1.54), keep the cement portion of the grade's ratio, and divide by the volume of one bag.
- Dry volume = length × width × depth × 1.54
- Cement volume = dry volume × (cement part ÷ total parts)
- Bags = cement volume ÷ 0.0347 m³ (one 50 kg bag)
Approx. cement bags per m³ of concrete
| Grade | Ratio | Bags / m³ |
|---|
| M10 | 1 : 3 : 6 | ~4.4 |
| M15 | 1 : 2 : 4 | ~6.3 |
| M20 | 1 : 1.5 : 3 | ~8.0 |
| M25 | 1 : 1 : 2 | ~11.1 |
Planning tool only. Follow your engineer's design mix for structural work.
Cement calculator FAQ
How many cement bags in 1 m³ of M20 concrete?›
About 8 bags of 50 kg cement per cubic metre for M20 (1:1.5:3), using the 1.54 dry-volume factor.
How many kg in one cement bag?›
A standard cement bag is 50 kg, which occupies roughly 0.0347 m³.
Does this include plaster and brickwork cement?›
This page sizes cement for concrete. Mortar for plaster and brickwork is shown in the brick calculator; a dedicated plaster mode is coming.