Sand Concrete (Dry Mix) kg to m³ Converter
Calculate volume yield from dry sand concrete mix bags. Adjust for bulk density. Ideal for estimating bags needed for posts, repairs, and screeds.
About
When purchasing pre-bagged sand concrete (also known as sandcrete or dry mortar mix), the primary challenge is determining how many bags are required to fill a specific volume. A common mistake is assuming 1 kg of dry mix yields 1 liter of wet concrete. In reality, the material compacts significantly when mixed with water.
This calculator converts the weight of dry mix into the resulting volume of wet concrete. It defaults to a standard bulk density of 2300 kg/m³, which is typical for general-purpose sand-cement mixes (M300, M150). Users can adjust this density based on specific manufacturer data found on the bag.
Formulas
The calculation relies on the relationship between mass, density, and volume. The density ρ represents the weight of the cured concrete per unit volume.
Where ρ is typically 2200 to 2400 kg/m³ for sand concrete.
Reference Data
| Bag Size | Yield (Liters) | Yield (m³) | Bags for 1 m³ |
|---|---|---|---|
| 20 kg | ~8.7 | 0.0087 | 115 |
| 25 kg | ~10.9 | 0.0109 | 92 |
| 30 kg | ~13.0 | 0.0130 | 77 |
| 40 kg | ~17.4 | 0.0174 | 58 |
| 50 kg | ~21.7 | 0.0217 | 46 |
| 1000 kg (Bulk) | ~435 | 0.435 | 2.3 |