Patio Stone Calculator
Plan a patio in one pass: how many stones the surface takes, plus the crushed gravel base and bedding sand underneath, in tonnes ready for the landscape yard.
Your results
Worked example
A patio is 4 m by 3 m, paved with 40 cm by 40 cm slabs and a 10% cutting allowance:
- Area: 4 m × 3 m = 12 m²
- One slab covers 0.40 m × 0.40 m = 0.16 m², so 12 ÷ 0.16 = 75 slabs, and 75 × 1.10 = 82.5, so 83 stones
- Base gravel: 12 m² × 0.10 m = 1.2 m³, at 1.6 tonnes per m³ = 1.92 tonnes
- Bedding sand: 12 m² × 0.025 m = 0.3 m³, at 1.6 tonnes per m³ = 0.48 tonnes
The stone count treats each slab as covering its full face size; narrow sand joints are absorbed by the cutting allowance on a patio this size.
How this calculator works
A standard Canadian patio build is 100 mm of compacted crushed gravel under a 25 mm screeded bedding sand layer, with the stones on top. Both materials are estimated at 1.6 tonnes per cubic metre, the standard planning figure for crushed gravel and dry sand. Gravel and sand results use the patio area without the waste allowance, since base materials do not get cut; order a little extra base gravel if your excavation runs deep.
Common questions
How thick should the gravel base be?
100 mm of compacted crusher run is the standard for a foot-traffic patio in most of Canada. In clay soil or where vehicles will cross, 150 mm or more is safer against frost heave.
Why is the bedding sand only 25 mm?
The sand layer is for levelling, not structure. Thicker sand beds shift under load. Screed it at 25 mm, lay the stones, then sweep polymeric or plain sand into the joints.
Estimates only. Results are provided for planning purposes and use the base depths and material densities stated on this page. Actual quantities vary with excavation depth, compaction, and stone pattern. Confirm amounts with your supplier before ordering. Mississippi Maple accepts no liability for purchase decisions made using this calculator.