Calculate one slab area
Convert the slab length and width to metres, then multiply them to obtain nominal square-metre coverage.
Divide the patio area by slab area
This gives a theoretical count before cuts, breakage and layout.
Mixed-size packs need the pack coverage
For real purchasing, use the exact manufacturer or supplier pack coverage where it is published—especially for mixed-size project packs. Single-size slab dimensions provide a theoretical face-area piece count, but joint widths and layout still come from the chosen paving system.
Allow for the actual layout
Curves, diagonal cuts and small edge pieces can increase waste compared with a simple rectangular patio.
Use the numbers in a calculator
Accuracy note
Where a figure depends on a product, supplier, installation method or project specification, use the current information for the exact material being purchased. The reference pages explain the maths and estimating logic; they are not a substitute for current technical data.