How to use this calculator
- 1Measure the length and width of the patio, path or driveway, or enter the area if you already know it.
- 2Choose your paver or slab, or pick “Other size” and type the real size from the product sheet. Check the joint width.
- 3Choose the shape and pattern. Simple shapes need about 5 % spare; curves and herringbone patterns about 10 %.
- 4Choose patio or driveway. The base depth fills in; make it deeper on clay, wet or frost-prone ground or if your paver maker asks for more.
- 5Read off the pavers to buy and how many tonnes or tons of base stone and bedding sand to order.
The formula
- 01Space one paver takes = (length + joint) × (width + joint)
- 02Pavers = area ÷ space one paver takes × (1 + spare %), rounded up
- 03Base area = (length + 2 × base depth) × (width + 2 × base depth)
- 04Base stone = base area × base depth × compacted density
- 05Bedding sand = area × bedding depth × density
Every paver takes up its own face plus one joint, so the joint is added to both sides of the size. Sizes on the label are often rounded: a “4 × 8 in” Holland paver is about 7¾ × 3⅞ in, which with ⅛ in joints works out at 4.57 pavers per square foot. With no joint at all, 200 × 100 mm block paving is exactly 50 per m².
The base is the part that carries the load. The Interlocking Concrete Pavement Institute (ICPI) asks for at least 100 mm (4 in) of compacted crushed stone under patios and paths and 150 mm (6 in) under home driveways on well-drained soil, and 50–100 mm (2–4 in) more in cold climates or on wet or weak soil. UK guidance is similar: about 100 mm of MOT Type 1 under a patio and 150 mm under a drive. Some paver makers ask for more, so follow the guide for your product.
Crushed stone shrinks when it is compacted, so the weight is worked out with the compacted density (about 2.1 t/m³, or 1.8 US tons per cubic yard). That weight is what you order: the looser stone the supplier delivers compacts down to the depth you entered. When the area is typed in directly, the base is worked out as if the area were a square, which slightly underestimates the extra edge on a long, narrow path.
Worked example
A 4 m × 3 m patio in 200 mm × 100 mm block paving with 3 mm joints works out at 47.83 per m², so 573.9 pavers before spares.
With 5% spare for cuts, buy 603 pavers.
A 100 mm base that runs past the edges is 1.344 m³ of compacted stone, about 2.82 t, and a 30 mm sand bed needs about 0.65 t of sand.
Tips before you buy
- Before you dig, find out where buried cables and pipes run (call 811 in the US; check utility maps or use a cable detector elsewhere).
- Dig out enough for the base, the bedding layer and the paver thickness together, and next to a house keep the finished paving at least 150 mm (6 in) below the damp-proof course, as UK guides advise.
- Buy all pavers from the same batch, and mix pavers from several pallets as you lay them so small colour differences blend in.
- Leave the final joint filling until the pavers have been compacted into the bedding sand, then sweep in joint sand and compact again until the joints are full.
- Keep a few spare pavers after the job. Matching them years later for a repair is often impossible.
Frequently asked questions
How many pavers do I need per square foot or square metre?
It depends on the paver size and the joint. A 4 × 8 in Holland paver works out at about 4.5 per ft², a 12 × 12 in patio stone just under 1 per ft², and 200 × 100 mm block paving about 48 per m² with 3 mm joints (50 with no joint). The calculator shows the exact figure for your size.
How deep should the base be for pavers?
ICPI's guidance is at least 4 in (100 mm) of compacted crushed stone under patios and walkways and 6 in (150 mm) under home driveways on well-drained soil, with 2–4 in (50–100 mm) more in cold climates or on wet or weak soil. Follow your paver maker's guide if it asks for more.
How much sand do I need under pavers?
Pavers sit on a thin screeded layer of coarse bedding sand, nominally 1 in (25 mm) and no more than 1½ in (40 mm) under ICPI's guide specification. UK guides use 25–40 mm of sharp sand. The bedding layer is not for levelling: fix high and low spots in the base instead.
How much extra should I order for cuts?
Oregon State University Extension advises adding 5 % for cuts, or 10 % if you know you will be cutting a lot of pavers: curves, herringbone or diagonal patterns, drains and steps. Small, fiddly areas may need a little more.
Can I lay pavers straight on the soil or on sand only?
Not if you want them to stay flat. Soil moves with the weather and sand alone spreads under load. A compacted crushed-stone base with an edge restraint is what stops pavers from sinking, rocking and spreading apart.
What sand goes between the pavers?
Fine, dry joint sand, kiln-dried sand or polymeric sand swept into the joints after the pavers have been compacted. It locks the pavers together. Coarse bedding sand can be used but is harder to sweep in.
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Sources
- ICPI Tech Spec 2 – Construction of interlocking concrete pavements (base thickness, joints)
- CMHA – Proper concrete paver base and depth: 4 in for patios, 6 in for residential driveways (ideal conditions)
- CMHA – Building your interlocking concrete pavement to last: edge restraints around the perimeter
- Alliance Gator – SuperSand G2 coverage per 50 lb bag
- CMHA (formerly ICPI) – Edge restraints: base extends past the restraint by the base thickness
- Oregon State University Extension – 10-step guide to installing pavers (5–10 % extra)
- Marshalls – How to lay block paving and patios (UK sub-base, laying course and joints)
Formulas last reviewed: September 30, 2026 ·How we check our formulas