How Many Paving Slabs Do I Need? A UK Guide
Published 27 July 2026 · Browse all tools
As a quick answer: divide your area in square metres by the coverage of one slab, then add 10% for wastage and round up. A 600 × 600 mm slab covers 0.36 m², so a 20 m² patio needs about 56 slabs before waste, or roughly 62 with a 10% allowance. Block paving works the same way but you're counting 50 blocks to the square metre. This guide gives you the per-square-metre figures for every common UK size, shows how the laying pattern changes the wastage, and works two real jobs through end to end. For the count on your own measurements, use the paving calculator.
Paving Calculator UK — work out your slabs and blocksSlabs per square metre — the numbers you actually need
Before any wastage, the whole job comes down to how much ground one slab covers. Take the plan size in millimetres, multiply the two dimensions, and divide a square metre by the result. It's easier to just read it off a table.
| Slab size | Coverage | Slabs per m² |
|---|---|---|
| 600 × 600 mm | 0.36 m² | 2.78 |
| 600 × 300 mm | 0.18 m² | 5.56 |
| 450 × 450 mm | 0.2025 m² | 4.94 |
| 400 × 400 mm | 0.16 m² | 6.25 |
| 300 × 300 mm | 0.09 m² | 11.11 |
The 600 × 600 mm slab is the workhorse of the modern UK patio, which is why it heads the list. If you're buying riven or textured slabs from Marshalls or Bradstone, check the pack coverage on the label, because a few ranges are sold at 590 × 590 mm to allow for a jointing gap, and that small difference shifts the per-m² figure.
Takeaway: most patios are 600 × 600 mm slabs at 2.78 to the square metre, but always check the pack label in case the range is undersized for jointing.
Block pavers per square metre
Block paving is more predictable because the size barely varies. The standard UK concrete block is 200 × 100 mm, covering 0.02 m², which gives exactly 50 blocks per square metre. That figure holds whether the block is 50 mm deep for a patio or 60–80 mm deep for a driveway, because depth affects the load it can carry, not how many fit on the surface.
The catch with blocks isn't the count, it's the cutting. A stretcher bond laid square wastes very little. A 45° herringbone, which is the pattern most people want on a driveway because it locks under vehicle loads, throws up a cut block at every edge and every change of direction.
Takeaway: block paving is a flat 50 per m², so your real variable is the wastage from the laying pattern, not the block itself.
Worked example — a slab patio
Say you're laying a patio behind a Rochdale semi, 5 m × 4 m, in 600 × 600 mm slabs, straightforward straight-coursed layout, so 10% wastage.
- Area = 5 × 4 = 20 m²
- Raw slabs = 20 ÷ 0.36 = 55.6
- With 10% wastage = 55.6 × 1.10 = 61.1, rounded up to 62 slabs
If those slabs come six to a pack, that's 11 packs, which gives you 66 and a bit of spare. Buy the 11 packs in one go from one batch. The bedding underneath is a 40 mm mortar bed, so the sand works out at 20 × 0.04 = 0.8 m³, about 1.28 tonnes, or two 850 kg bulk bags of sharp sand mixed roughly 4:1 with cement.
Takeaway: 20 m² of 600 × 600 mm slabs comes out at 62 with 10% waste — round up to full packs and you'll have a sensible margin without overspending.
Worked example — a block paving driveway
Now a driveway, 6 m × 4 m, 200 × 100 mm blocks, 45° herringbone, so 15% wastage for the cuts.
- Area = 6 × 4 = 24 m²
- Raw blocks = 24 × 50 = 1,200
- With 15% wastage = 1,200 × 1.15 = 1,380 blocks
Blocks are usually sold by the square metre or in packs covering a set area, so order 24 m² plus the 15%, which is 27.6 m² of coverage. The laying course is 50 mm of sharp sand: 24 × 0.05 = 1.2 m³, about 1.9 tonnes, or three 850 kg bulk bags. On top of that you brush kiln-dried jointing sand into the gaps, roughly one 25 kg bag per 11 m², so three bags here.
Takeaway: the same 24 m² needs 1,200 blocks square-laid but 1,380 in herringbone — the pattern adds 180 blocks, so decide the pattern before you order.
How much wastage to actually allow
The blanket "add 10%" you'll see everywhere is a decent middle guess, but it's worth being more specific because it changes the bill.
- 5% — full slabs, stack bond or straight courses, square area with clean edges.
- 10% — standard bonds, the odd cut, a mostly rectangular area.
- 12–15% — 45° herringbone block paving, circles, curves, diagonal patterns, or any job with lots of edge cuts.
There's a second reason to round up generously that has nothing to do with cutting: concrete paving is dyed in batches, and the shade drifts slightly from one production run to the next. If you come up two slabs short and buy a top-up pack a fortnight later, there's a real chance it won't match the rest of the patio in daylight.
Takeaway: set your wastage from the pattern, not a flat 10%, and lean high — running short risks a colour mismatch you can't easily fix.
Don't forget what's under the paving
The slab or block count is only the visible layer. Under it sits a compacted Type 1 MOT sub-base, usually 100 mm for a patio and 150 mm or more for a driveway that takes a car, plus the sand laying course and edge restraints to stop the whole thing spreading. None of that is in the slab count, but it's most of what makes paving last. For the sub-base quantity, the gravel and sub-base calculator does the Type 1 layer, and the mortar calculator covers the bedding mix for slabs.
Takeaway: budget for the Type 1 sub-base, laying course and edging separately — they're not in the slab count but they decide whether the job survives its first winter.
What paving costs in 2026
Rough UK materials prices at the time of writing, excluding sub-base, labour and delivery:
- Concrete block pavers: around £10–£18 per m² for standard ranges; more for premium or aged/tumbled blocks.
- Concrete paving slabs (600 × 600 mm): around £18–£35 per m² depending on finish.
- Porcelain and natural stone slabs: £30–£70+ per m², sometimes higher for premium stone.
- Sharp sand (bulk bag, ~800–850 kg): around £50–£75 from Travis Perkins or Jewson.
- Kiln-dried jointing sand (25 kg): around £6–£10.
For the full installed cost including sub-base and labour rather than just materials, the driveway cost calculator gives an installed range.
Takeaway: budget the pavers as a per-m² materials figure, then add sub-base, sand and labour on top — the paving itself is often the smaller half of a driveway bill.
The thing most guides skip
Most guides stop at "divide the area, add 10%" and leave it there. The bit that catches people out isn't the sum, it's the ordering. A groundworker I spoke to always orders a full extra pack over what the maths says, and won't split the difference by ordering "about right." His reasoning was simple: if he's a few slabs short three days into a job, the merchant either has a different batch or none at all, and matching concrete slab colour after the fact is close to impossible. A single leftover pack in the garage is cheap insurance; a patio with one visibly paler corner is a callback he's not doing for free.
The same logic applies to blocks, but it bites harder on slabs because the units are bigger and a mismatch is more obvious. Order the whole quantity, wastage included, in one delivery from one batch, and you sidestep the problem entirely.
Takeaway: order the full quantity plus a margin in a single batch delivery — a spare pack costs a few pounds, a colour-mismatched corner costs the whole look.
Summing up
Work out your area, divide by the coverage of one unit (0.36 m² for a 600 × 600 slab, 0.02 m² for a standard block), add wastage set by your laying pattern rather than a flat 10%, and round up to full packs from a single batch. Add the bedding sand from the bed depth, and remember the sub-base and edging aren't in that count. For the exact figures on your own measurements, including sand and an optional cost, run them through the calculator below.