Hardcore and sub-base calculator
Work out how much hardcore or MOT Type 1 you need under a patio, path or drive.
Uses only the sizes you enter.
Show the workings
| Step | Sum | Answer |
|---|---|---|
| Volume | 20 m² × 0.1 m deep | 2 m³ |
| In litres | 2 × 1,000 | 2,000 litres |
Where the figures come from
- Litres in a cubic metre: 1,000 litres per m3. Source: Weights and Measures Act 1985, Schedule 1. Checked 13 November 2026.
How much hardcore do I need?
Multiply the length and width, in metres, by the depth of the sub-base, in metres. A patio 5 m by 4 m on 100 mm (0.1 m) of sub-base needs 5 × 4 × 0.1 = 2 cubic metres before it is compacted.
Hardcore packs down when it is compacted, so it takes more loose material to fill a depth than the volume suggests. Use "Extra to allow" for that, and ask your supplier how much to add for their material.