Sand calculator

Loose sand weighs about 1.6 tonnes per cubic metre, so one tonne covers roughly 10 square metres at 60 mm deep. Multiply area by depth for volume, then by the density. Sand compacts as it is screeded, so order about 10% over the raw figure.

Three sands do three different jobs and are not interchangeable. Sharp sand is coarse and angular, used for laying slabs, screeding and mixing concrete. Building sand — also called soft sand — is fine and rounded, used for mortar where workability matters more than strength. Kiln-dried sand is sharp sand dried and graded for brushing into block-paving joints, and it is the only one that will actually run into a 3 mm gap. Buying the wrong one is the most common mistake on this list, and it does not become obvious until the mortar will not hold or the paving beds unevenly.