The formula
Slabs = patio area ÷ slab area, plus cutting allowance, rounded up. Sub-base volume = area × depth (mm) ÷ 1,000. Tonnes = volume × density.
Garden • UK CALCULATOR
Paving Slab Calculator UK
Plan a rectangular patio with slab quantities and a separate estimate for its granular sub-base. Choose the slab dimensions and actual construction depths used for your project.
▦
Your estimate starts here
Enter your measurements and calculate to see materials, quantities and an optional price estimate.
GOOD TO KNOW
How this calculator works
Worked example
A 4 m × 3 m patio covers 12 m². With 600 × 600 mm slabs, that is approximately 34 slabs before cutting allowance.
Check before ordering
This is a buying estimate, not a construction design. Joint widths, laying patterns, border cuts, fall, drainage, ground conditions and bedding materials are not fully modelled. Check local advice for the required sub-base specification.