Sub Base Calculator UK
Work out how much sub-base material you need for patios, driveways and garden paths. Choose from MOT Type 1, hardcore, crushed concrete or crushed stone - with compaction factor applied automatically.
Enter dimensions
Enter the finished compacted depth
Covers cuts, breakages and uneven ground. 10% is a typical starting point.
Sub-base estimate
Enter dimensions to see estimate
How to calculate sub-base quantities
The calculation is length × width × compacted depth, multiplied by a compaction factor to account for the difference between loose-tipped material and the final compacted layer. The result is converted to tonnes using the material density.
Entering your required compacted depth is important - this is the depth you need after compaction, not the depth of material you tip. Our calculator adds the compaction factor automatically based on the material you select.
Worked example - 4m × 3m patio at 100mm compacted
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Frequently asked questions
Planning estimates only
These results are estimates for planning purposes only. Actual material quantities can vary based on site conditions, compaction, wastage, product size, installation method and supplier guidance. For structural, safety-critical or regulated work, always consult a qualified professional.