How many paving slabs do I need?
Lay a patio, path or paved area — enter the size and your slab dimensions and get the number of slabs to buy with wastage, plus the hardcore sub-base, sharp sand and cement for the bed. Buy a little over: ranges change, so a later batch may not match. Free, no sign-up.
A guide, not a guarantee. Sub-base assumes compacted MOT Type 1 at about 2 tonnes per m³; bedding assumes a full sharp-sand-and-cement mortar bed at roughly 1:5. Densities and how you mix vary, so order a little over and keep a few slabs spare — ranges change, so a later batch may not match. Jointing compound, a sub-base membrane, edge restraints and a sealer are all extra. Nothing you type leaves your browser.
Area, slab size, sub-base and bedding.
Start with the area. Length times width gives the area in square metres; add an L-shape, path or step with the extra-area box. We add a wastage percentage on top for the cuts you can't avoid around the edges and obstacles.
Divide by one slab. A 60×60 cm slab covers 0.36 m². We divide the area-plus-wastage by one slab and round up, so you're never short across the last row.
The sub-base. Slabs sit on compacted MOT Type 1 hardcore — about 100 mm for a patio, 150 mm where a car crosses it. We work out the volume and convert to tonnes at roughly 2 tonnes per cubic metre, then to one-tonne bulk bags. Always compact it in layers with a wacker plate.
The bedding. Slabs are laid on a full sharp-sand-and-cement mortar bed (about 1:5), not on five dabs — dabbed slabs rock and crack. We size the sand by volume and the cement at roughly six 25 kg bags per tonne of sand.
What this leaves out. Jointing compound or mortar for the gaps, a weed-suppressing sub-base membrane, edge restraints, a sealer, and a fall of about 1:80 away from the house so water drains. If a landscaper is laying it, get their take-off too — they carry the risk of ordering short.
Keep every outdoor job in one place.
Stead remembers your garden's measurements, the materials you chose and when each job was done — so the next project starts with the numbers already to hand.