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Home & DIY calculator

Pavers / Patio Slabs Calculator

Enter your patio size and paver size to get pavers, base, sand, and edging needed.

Part of: Garden & landscaping

Your measurements

Metric + imperial

How this calculator works

Pavers per m2 = 1 / [(paver length + joint) x (paver width + joint)]. Pavers = round up(patio area x waste factor x pavers per m2). Base and sand volumes reuse the gravel formula (area x depth x density) at their own depths. Edging pieces = round up(perimeter / edging piece length).

Worked example

A 4 m x 3 m patio (12 m2, 10% waste = 13.2 m2) with 400 x 400 mm slabs and a 3 mm joint needs 82 slabs, a 10 cm sub-base layer, a 5 cm sand bedding layer, and edging pieces for the 14 m perimeter.

Assumptions to check

  • This combines the whole patio project (pavers + base + bedding sand + edging) in one result, following the same combined-output pattern as the fence calculator, rather than a bare paver-count tool.
  • Base and bedding depths are common defaults (10 cm compacted sub-base, 5 cm sand bed) - both are editable, since sub-base depth depends on ground conditions and traffic load.
  • Grouting/pointing material between pavers is not included - only the base, bedding sand, and edging.

Read the calculation and QA methodology →

Common questions

FAQ

Do I need a sub-base under a patio?

Most patios need a compacted sub-base (crushed stone/hardcore) below the bedding sand, especially over soft or clay soil - depth depends on ground conditions; a landscaper can advise for your site.

How much extra should I order for cuts?

A 10% allowance covers most rectangular patios; add more for diagonal or complex layouts, curved edges, or irregular-shaped areas.

What is the joint gap for?

A small gap (often 2-5 mm for tight-jointed pavers, more for flagstone-style paving) is left between pavers for jointing sand or mortar - adjust to match your chosen paver and jointing method.

Why can the slab count differ from a face-area calculation?

The estimate uses each slab plus the joint gap as its installed module, then rounds the purchase quantity up after applying your waste allowance. A face-area calculation that ignores joints or rounds only once can produce a different count.

What should I check before ordering?

Confirm the supplier’s actual slab dimensions, jointing method, pack quantity, edge cuts, delivery access, and whether their recommended base depth differs from your ground and intended use. The calculator does not include jointing material, drainage design, labor, or structural advice.