Paving slabs calculator
Free toolEnter the area to cover and the size of your slabs or pavers to find out how many units to buy, waste margin included.
Units needed
Enter the data and press "Calculate units" to see the result.
How to use it
- Enter the length and width of the area to pave.
- Set the slab dimensions.
- Adjust the waste if needed and read the number of slabs.
What it works out and how
The area is increased by the waste allowance, 8% by default, and divided by the area of one slab, rounding up. Waste covers perimeter cuts and slabs that arrive broken or crack while being laid. If you leave wide joints between slabs you will need slightly fewer, so the result errs on the safe side.
Frequently asked questions
What waste should I use for a curved patio?
Go up to 12 or 15%. Curved edges and diagonal layouts multiply cuts and unusable offcuts.
What base do slabs need?
The usual build-up is 10 to 15 cm of compacted sub-base with a bed of sand or mortar on top. A poor base is the main cause of rocking slabs.
Does it need a slope?
Yes. A fall of 1 to 2% away from the house prevents puddles.