The answer
For a 4m × 3m patio (12 m²) you need 39 slabs of 600×600mm — that is 35 laid 7 across by 5 down, plus 10% for cuts — along with 2.16 tonnes of MOT Type 1 (about 3 bulk bags) and 0.77 tonnes of sharp sand (about 31 × 25kg bags) for a 40mm bed.
| Paving angle | 4 m × 3 m |
|---|---|
| Area | 12 m² |
| Slabs before waste | 35 (7 across × 5 down) |
| Waste allowance | 10% |
| Slabs to order | 39 |
| MOT Type 1 sub-base | 2.16 t at 100 mm — 3 bulk bags (850 kg) |
| Sharp sand bedding | 0.77 t at 40 mm — 31 × 25 kg bags or 1 bulk bag(s) |
| Edge restraint | 14 m of open perimeter |
Will it fit the layout without cuts?
Neither run divides neatly, so expect cuts along two edges. Set the grid out from a straight edge before you lay anything: a dry run of the first row tells you where the cut slabs land, and it is better to find that out on the grass than on the bedding sand.
What you actually order
| Material | Quantity | Notes |
|---|---|---|
| Paving slabs 600 × 600 mm | 39 slabs | 7 × 5 = 35 plus 10% for cuts. |
| MOT Type 1 sub-base | 2.16 tonnes | ≈ 3 × 850 kg bulk bags at 100 mm compacted. |
| Sharp sand (bedding) | 0.77 tonnes | ≈ 31 × 25 kg bags, or 1 bulk bags, at 40 mm. |
| Jointing sand or paving grout | estimate only | Check the manufacturer's coverage for your joint width. |
| Edge restraint / kerb and concrete haunch | 14 m | Rule of thumb: the open perimeter, 14.0 m here. An edge that is not restrained lets the paving spread — a kerb on a concrete haunch, or a proprietary edge, is what holds it. Only the edges that meet soil or a drop need it. |
Figures are planning estimates, not a quote. Merchants round loosely on aggregates, and slab packs vary by range.
Adjust it for your own patio
The calculator below is filled in with the same figures. Change the slab size, the sub-base depth or the waste allowance and everything updates — including the shopping list.
Open the full paving calculator with these figures
The full calculator also draws the slab layout to your measurements and can send the quantities to the Project Planner.
Common questions
How many 600×600mm slabs do I need for a 4m × 3m patio?
A 4m × 3m patio is 12 m². Laid with 600×600mm slabs and 10mm joints it works out at 7 across by 5 down, which is 35 slabs. With 10% for cuts and breakages you should order 39.
How much MOT Type 1 do I need for a 4m × 3m patio?
At a 100mm compacted depth, 12 m² needs 1.2 m³ of sub-base. At 1.8 tonnes per cubic metre that is 2.16 tonnes, or 3 standard 850kg merchant bulk bags.
How much sharp sand for the bedding?
A 40mm bedding layer over 12 m² is 0.48 m³. At 1.6 tonnes per cubic metre that is 0.77 tonnes — about 31 × 25kg bags, or one bulk bag.