Hardcore Calculator

Calculate how much hardcore fill you need in tonnes and cubic metres for foundations and sub-bases.

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How to Use This Calculator

How to Use

  1. Enter the length and width of the area you are filling.
  2. Enter the finished compacted depth of hardcore.
  3. Add a compaction allowance (10–20%) so you order enough to whack down to depth.

Tips

  • Hardcore weighs about 1.9 tonnes per cubic metre.
  • Use 150 mm (6 in) under slabs and driveways; more for soft ground.
  • Blind the surface with sand or fines before laying a slab or sub-base.

Common Questions

What is hardcore used for?

Hardcore is crushed brick, concrete or stone used as a compacted base under slabs, driveways, foundations and floors to provide a stable, free-draining layer.

How much does hardcore weigh?

Hardcore weighs roughly 1.9 tonnes per cubic metre, though it varies with the material it is made from.

How thick should a hardcore layer be?

A typical compacted hardcore layer is 150 mm (6 in) under slabs and driveways. Soft or uneven ground may need more.

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