### Gravel Calculator

A 20mm aggregate would need to be at least 40-50mm deep, and at least 50-60mm on driveways. A larger aggregate will settle and bond together better than smaller ones. The depth you will need to select for your gravel or slate will always depend on the aggregate size and what the surface will be used for. Example gravel estimate . We estimate an area of 5 metres by 5 metres, with a depth of