Free Online Calculators
Area + stone size → count, grit & sand quantities
The paving stone calculator works out stones per m², the total number of stones and the bedding grit and sub-base in tonnes from area, stone size, joint width, laying pattern and sub-base depth. Waste is fixed by pattern: 5 % running bond, 10 % herringbone, 12 % diagonal. A 24 m² patio with 450 × 450 mm slabs in running bond needs 123 slabs.
With 20 × 10 cm pavers and a 3 mm joint you need 47.8 pavers per m²; a 10 × 1 m garden path takes 503 with 5 % waste. Underneath go 4 cm of bedding grit (0.72 t for 10 m²) and the sub-base — 3.6 t of crushed stone at 20 cm. The table covers nine common sizes.
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| Size | Pavers/m² | 10 m² + 5 % | 20 m² + 10 % (herringbone) |
|---|---|---|---|
| 10 × 10 cm | 94.3 | 990 | 2,074 |
| 20 × 10 cm | 47.8 | 503 | 1,053 |
| 16 × 24 cm | 25.2 | 266 | 556 |
| 20 × 20 cm | 24.3 | 255 | 534 |
| 30 × 20 cm | 16.3 | 171 | 358 |
| 40 × 20 cm | 12.2 | 129 | 269 |
| 40 × 40 cm | 6.2 | 65 | 136 |
| 60 × 30 cm | 5.5 | 58 | 121 |
| 60 × 40 cm | 4.1 | 44 | 91 |
A 10 × 1 m path (about 33 × 3 ft) takes 503 pavers of 20 × 10 cm including 5 % waste, or 255 of 20 × 20 cm. Allow 10 % for herringbone patterns.
24.3 with a 3 mm joint — exactly 25 without joints.
Usually 15–20 cm (6–8 in) of compacted crushed stone plus 3–5 cm of bedding for footpaths, and 30–40 cm for driveways. At 20 cm, 10 m² need 3.6 t of base and 0.72 t of bedding.
Whether you are laying a garden path or a patio, knowing how many paving stones to order saves a second trip to the builder's merchant. This paving calculator asks for the area, the length and width of one stone, the joint width, the laying pattern and the sub-base depth, plus an optional price per stone.
It shows stones per m² (stone size plus joint), the total number of stones including waste, the bedding grit in tonnes, the sub-base in tonnes and, if you enter a price, the material cost of the stones. Joint sand and edging stones are not included.
Example: a 4 m × 6 m patio (24 m²) with 450 × 450 mm slabs, a 3 mm joint and a running bond needs 4.9 slabs per m², so 123 slabs including 5 % waste. With a 10 cm sub-base, the calculator shows 4.3 t of sub-base and 1.7 t of bedding.
The waste allowance is fixed by the pattern you choose: 5 % for a running bond, 10 % for herringbone and 12 % for diagonal. There is no separate waste field, so for areas with many curves or obstacles order a few extra stones. With the default 20 × 10 cm pavers and 3 mm joints, 50 m² take 2,511 pavers in running bond, 2,631 in herringbone and 2,679 laid diagonally.
Under the pavers go a compacted sub-base of crushed stone and a bedding layer. The calculator uses a fixed 4 cm bedding layer and 1.8 tonnes per m³ for both layers; you set the sub-base depth yourself. Footpaths and patios often get 15–20 cm, driveways more, depending on the ground and the design.
Edging is not part of the result, so work it out from the perimeter. A 1 m × 20 m garden path has 42 m of perimeter; with 250 mm edging units that is 168 pieces, fewer where the path meets a wall or the house.
Divide 1 m² by the area of one paver including the joint, multiply by your area and add waste for your pattern. The calculator does exactly that: for 600 × 600 mm slabs with a 3 mm joint it gives 2.75 per m², so a 15 m² patio in running bond needs 44 slabs.
10 %. Running bond uses 5 % and diagonal 12 %. The values are fixed; add extra pieces yourself if your area is irregular.
It gives the bedding grit for a 4 cm layer and the sub-base for your chosen depth, both in tonnes. Joint sand is not included.