Work out concrete mix ratio instantly with clear inputs, formula shown and shareable results.
Dry ingredients bulk down when mixed with water, so the dry volume is taken as 1.54 times the wet concrete volume. That dry total is then split by the mix ratio, and cement volume is converted to bags using a bulk density of 1440 kg/m³.
Dry volume
dry volume = wet volume × 1.54
Ingredient split
ingredient = dry volume × part / (sum of parts)
Dry volume 1.54 m³ split seven ways gives 0.22 m³ cement, 0.44 m³ sand and 0.88 m³ aggregate, about 6.34 bags of 50 kg cement.
Voids between the dry particles fill with cement paste and water during mixing, so more dry material is needed than the finished volume suggests.