Calculating paving stones: formula and practical tips
Wastage, laying patterns and base construction
Calculating the number of paving stones needed is simple area math: number = total area ÷ single stone area, rounded up and including wastage. For a standard concrete paving stone measuring 10 × 20 cm, the stone area is 0.02 m² – so one square metre of area needs 50 stones (net). With 5% wastage, that becomes 52.5, so 53 stones per m² are needed.
Base construction is critical: The quality of a paved surface depends 80% on the base. A typical build-up for a car driveway: remove 25 cm of topsoil → 15 cm gravel sub-base (0/32 mm mix, compacted) → 3–5 cm chippings bedding layer (2/8 mm, not compacted) → lay paving stones → brush in joint sand. Without an adequate sub-base, settling and puddles will occur.
Laying pattern and wastage: The most economical laying pattern is the stretcher bond (parallel to the edges), because it produces almost no cutting waste. The running bond (offset by half a stone length) looks more attractive and is structurally more stable. Circular patterns and herringbone patterns require many diagonal and angled cuts – plan for 10% wastage here. Allow even more for borders and curved paths.
Natural stone vs. concrete paving: Granite and basalt paving lasts longer (100+ years) but costs 3–5 times more than concrete paving. Concrete paving fades after 10–20 years, while natural stone develops a patina and looks more attractive over time. For driveways with vehicle loads, concrete paving stones must be at least 6 cm thick; 6 cm is sufficient for footpaths, 8 cm for car driveways, and 10 cm for areas used by trucks.