Concrete Mix Ratio
Split a concrete volume into cement, sand and aggregate by a volume ratio (1:2:4 …) with your dry-volume factor, bulk densities, bag size and w/c ratio.
Loose volume of each material, masses and cement bags from the densities you enter, water from the w/c ratio — every factor yours, and the batching caveat stated.
Example: 2 m³ at 1:2:4 with a dry-volume factor of 1.54 needs 0.44 m³ of cement (634 kg, 13 bags of 50 kg at 1,440 kg/m³), 0.88 m³ of sand and 1.76 m³ of aggregate; w/c 0.5 → 317 L of water.
A volume ratio,
split honestly.
What the ratio means, why a dry-volume factor is needed, and why every number is yours.
The split
A mix ratio such as 1 : 2 : 4 is by loose volume. The placed (wet, compacted) volume you need is multiplied by your waste allowance and by the dry-volume factor, then divided in the ratio: cement gets 1/7, sand 2/7, aggregate 4/7 of the loose volume.
The dry-volume factor
Loose cement, sand and stone occupy more space than the concrete they compact into: water fills voids, air is driven out, and sand bulks with moisture. Mix designs and suppliers quote a factor for their materials; it is an input here and not assumed, because it varies with the materials and the method.
Masses, bags and water
Masses need bulk densities (from the supplier or bag) — none is embedded. Cement bags follow from the bag mass you enter; water from the water–cement ratio by mass. Volume batching is a purchasing estimate, not a structural mix design: strength and workability come from a design or a specification. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- Volume batching by mix ratio: loose volume = placed volume × waste × dry-volume factor, split in the stated parts (standard site practice; the factor and densities are user inputs, none embedded)
Last reviewed 20 September 2026. How results are checked: How we verify.