How the paver calculator works
A paved surface is three layers: the pavers you see, a thin bed of sharp sand they sit in, and a thicker layer of compacted crushed stone that carries the load and drains water. The calculator works out each layer from the same footprint. The paver count is the area divided by the face of one paver, plus an allowance for the pieces cut at edges. Most concrete pavers have small spacer nibs, so their nominal size already includes the narrow sand joint.
Pavers = area ÷ (paver length × paver width) × (1 + cuts) · Base = area × depth × 2.1 t/m³ · Sand = area × bed depthThe base weight uses 2.1 tonnes per cubic metre, a typical figure for dense-graded crushed stone (crusher run, road base or MOT Type 1) once it is compacted. Because the calculator measures the compacted depth, that weight is what you need to order: the loose material from the truck will fill about a quarter more volume until the plate compactor has been over it.
Worked example
A 6 m × 3 m patio covers 18 m². Block pavers of 200 × 100 mm have a face of 0.02 m², so 18 ÷ 0.02 = 900 pavers, and 990 with a 10% cutting allowance. A 10 cm compacted base takes 18 × 0.10 = 1.8 m³ of crushed stone, which weighs 1.8 × 2.1 = 3.78 tonnes. A 3 cm bed of sand adds 0.54 m³. In US units, a 20 × 10 ft patio in 4 × 8 in pavers needs 900 pavers before cuts, a 4 in base of about 2.5 yd³ and 0.6 yd³ of sand for a 1 in bed.
Common paver sizes
| Paver | Per m² | Per ft² | Typical use |
|---|---|---|---|
| 200 × 100 mm block | 50 | 4.6 | Driveways, herringbone patios |
| 4 × 8 in brick paver | 48.4 | 4.5 | Paths, edging, basket-weave |
| 6 × 9 in | 28.7 | 2.7 | Patios, walkways |
| 12 × 12 in | 10.8 | 1.0 | Patios, stepping areas |
| 300 × 300 mm slab | 11.1 | 1.03 | Paths, small terraces |
| 600 × 600 mm slab | 2.78 | 0.26 | Terraces (usually on a mortar bed) |
Pavers 60 mm (2⅜ in) thick are standard for foot traffic and light cars; 80 mm (3⅛ in) is recommended where vehicles turn or park often.
Mistakes to avoid
- Skimping on the base. Ruts and sunken pavers are almost always a base problem. Compact in layers of about 5–7 cm (2–3 in), not in one thick lift.
- Using sand to fix levels. The sand bed should be one uniform depth; dips in the base are corrected with more stone, never with extra sand.
- Forgetting the edge restraint. Without a fixed edge of plastic, metal or concrete haunching the outer rows creep outward. Extend the base about 15 cm (6 in) beyond the paved edge to support it.
- Excavating too little. The dig depth is base + sand + paver thickness: about 19 cm for the example above.
- Ignoring fall. Give the surface a slope of about 1:60 to 1:80 away from the house so rain runs off.
A reproducible calculation with complete inputs
For a reproducible paver calculator example, use the metric input system and enter Area length: 6 m; Area width: 3 m; Paver size: 200 × 100 mm block paver; Gravel base depth (compacted): 10 cm; Sand bed depth: 3 cm; Cutting allowance: 10 %. These settings describe one specific scenario, not a new default for every job. The result follows the method and allowances already explained above. Keep the entire set of values when comparing it with a hand calculation; omitting a selected material or an allowance can change the result even when the dimensions match. The following rows show the unrounded calculation values alongside the precision used by the interface.
| Result | Calculation value | Displayed value | Unit |
|---|---|---|---|
| Pavers to buy | 990 | 990 | |
| Paved area | 18 | 18.0 | m² |
| Base gravel | 1.8 | 1.80 | m³ |
| Base gravel weight | 3.78 | 3.78 | t |
| Bedding sand | 0.54 | 0.54 | m³ |
Frequently asked questions
How many pavers do I need for a 10x10 patio?
A 10 × 10 ft patio is 100 ft². With 4 × 8 in pavers at 4.5 per ft² that is 450, or 495 with a 10% cutting allowance; with 12 × 12 in pavers it is 100, plus 10 for cuts.
How much gravel do I need under pavers?
For a patio, 4 in (10 cm) of compacted crushed stone: about 1.2 yd³ or 2.2 US tons per 100 ft², or 0.1 m³ and 0.21 tonnes per square metre.
How much sand do I need for pavers?
A 1 in bed needs about 0.31 yd³ per 100 ft² (0.25 m³ per 10 m² at 2.5 cm), plus a few bags of joint sand to sweep in once the pavers are laid.
How many pavers are in a square metre?
Fifty standard 200 × 100 mm block pavers make one square metre, as do about 48 brick pavers of 4 × 8 in.
How deep should I dig for a paver patio?
Add the base, sand and paver thicknesses: 10 cm + 3 cm + 6 cm = 19 cm (roughly 7 in) for a patio, and considerably deeper for a driveway on soft soil.