How Much Paving Do I Need? Working Out Coverage
Multiply length by width in metres to get your area in m², add about 10% for cuts and breakages, then round up to whole packs. Paving is sold by coverage — packs state their m² — so a 20m² patio needs roughly 22m² of slabs. A coverage calculator does all of this in seconds.
The arithmetic is three steps: measure your area in square metres (length × width), add about 10% for cuts and breakages, and round up to whole packs. Paving is sold by coverage — every pack states the m² it covers — so a 4m × 5m patio (20m²) needs roughly 22m² of slabs, which then rounds up to the nearest pack size. The coverage calculator does all three steps, converts to slab and pack counts, and shows the price in all three units.
Why the 10% allowance is not optional
Every real patio has perimeter cuts, and cut slabs usually can't donate their offcuts elsewhere; occasional transit breakage happens even with a guarantee behind it; and a batch-matched spare slab today is worth three phone calls in two years. Skipping the allowance is the most common way DIY projects stall mid-lay — a top-up order costs delivery time, and natural-stone batches shift subtly between quarryings.
Odd shapes
Break L-shapes and multi-level layouts into rectangles, calculate each and sum them. Circles: πr² (a 3m-diameter circle is about 7.1m²) — then let the allowance absorb the curved cutting, which is exactly what it's for. Diagonal laying patterns increase cutting waste; nudge the allowance up rather than down.
Slabs per square metre
It depends entirely on the format: a 900×600mm slab covers 0.54m² (about 1.85 slabs per m²), a 600×600mm slab 0.36m² (about 2.8 per m²). Don't memorise it — the product page states m² per slab and per pack for each range, and the calculator reads those numbers directly.
Beyond the slabs
Quantity isn't only slabs: MOT Type 1 sub-base, bedding sand and cement, priming slurry (for porcelain) and jointing product all scale with the same area — the ground-prep guide covers the build-up so the whole order arrives together. Colour check first: order a sample before committing pallets.
Common questions, answered straight
How do I work out how many paving slabs I need?
Measure the area in m² (length × width), add about 10% for cuts and breakages, then divide by the m² each slab covers and round up to whole packs. A coverage calculator does this in seconds from the product's real pack data.
How much extra paving should I order for wastage?
About 10% over the measured area — more for diagonal patterns or heavily cut layouts. The allowance covers perimeter cuts, occasional breakage and a batch-matched spare.
How many 900x600 slabs per square metre?
Each 900×600mm slab covers 0.54m², so about 1.85 slabs per m². A pack of 40 covers 21.6m².
How do I calculate paving for a circle or odd shape?
Split odd shapes into rectangles and sum them; for circles use πr². Curved cutting consumes more waste, so keep the full 10% allowance or a little more.
Pave Direct Ltd · Blue House Farm Yard, Deeping St Nicholas, PE11 3DH · 01778 343999