Patio paver calculator

Pavers are the number everyone works out. The base is the number that fills the truck. This does both — pavers, bedding sand, compacted aggregate base, and edge restraint — for a rectangular patio, in imperial or metric.

01 How the math works

Four separate take-offs share one footprint. Get the footprint right and the rest follows.

Paver count is area times coverage, where coverage is a plain identity: 144 ÷ (paver length × width) in inches. A 4 × 8 paver is 4.5 per ft²; a 6 × 6 is 4.0; a 12 × 12 is 1.0. Pavers lay tight with sand-swept joints, so unlike brick you add nothing for the joint. Multiply, add cutting waste, round up to whole pavers.

Bedding sand is the paver area under a 1 in (25 mm) screeded layer. The base is thicker and bigger: it sits under the sand at the depth the soil calls for, and it runs past the pavers on every open side so the edge restraint has something solid to grip. Edge restraint is the open perimeter — every side not held by the house or a wall.

02 Worked example

Take a 10 ft × 12 ft backyard patio (3.05 m × 3.66 m), 4 × 8 Holland pavers, a 4 in base, a 1 in sand bed, and the base run 6 in past the pavers.

Pavers: 120 ft² (11.15 m²) × 4.5 per ft² = 540 pavers. Add 5% for edge cuts and breakage: 567 pavers.

Bedding sand: 120 ft² × (1 in ÷ 12) = 10 ft³ (0.28 m³), about 1,000 lb (454 kg) of washed concrete sand.

Base: the base runs 6 in past the pavers on each side, so the base footprint is 11 ft × 13 ft = 143 ft² (13.29 m²), not the 120 ft² of the patio. At 4 in deep that is 47.67 ft³ = 1.77 yd³ (1.35 m³) of crushed stone, about 4,767 lb — 2.38 tons (2,162 kg).

Edge restraint: the open perimeter is 44 lin ft (13.41 m), around 44 spikes at 12 in on center. If one 12 ft side butts the house, drop that side and you need restraint on 32 lin ft.

03 When this calculator is wrong

The paver count is the easy part of a paver order. The base is where the estimate quietly goes short.

• The base is bigger than the patio. ICPI/CMHA Tech Spec 3 puts the base at least 6 in (150 mm) past the pavers on every open side, so the edge restraint spikes into compacted stone instead of loose fill. On a 10 × 12 patio that is 143 ft² of base against 120 ft² of pavers — 19% more base than the footprint. Calculators that use the patio footprint under-order the base by that margin.
• Base depth is a soils question, not a constant. Tech Spec 2 sets 4 in (100 mm) compacted for a patio and 6 in (150 mm) for a residential driveway over well-drained soil. Poorly drained or frost-prone ground, and any vehicle heavier than a car, push it to 8–12 in (200–305 mm). Tonnage scales straight with depth — a 6 in base is 50% more stone than a 4 in one.
• Pattern drives the waste factor. The default 5% suits a straight running-bond or stack layout. A 45° herringbone throws a triangular cut at every border paver; treat it like the TCNA tile figures and budget 10% or more.
• Nominal size is not the milled size. The 4.5-per-ft² identity uses a nominal 4 × 8. Real units run a touch under nominal and carry spacer nubs, so a manufacturer's stated pieces per ft² can sit a few percent above the identity. Where the two disagree, the pallet label wins.

04 What to do with the result

Order pavers to the piece or the pallet your supplier sells, rounded up — a spare row is cheaper than a return trip for a dye lot that no longer matches. Give the yard the base and sand as volume: 47.67 ft³ is 1.77 yd³, and aggregate sells by the cubic yard or the ton.

On the base, round up and never down. Returning a half-ton of crushed stone costs almost nothing; a second delivery to finish a base you cut too close costs a delivery fee and a day. The one place to buy exactly is the pavers themselves — once a color lot is gone, the replacement will not match, so a modest overage beats a mid-project shortfall you can not refill.

05 Common questions

How many pavers do I need per square foot?

It is a plain identity: 144 ÷ (length × width) in inches. A 4 × 8 in paver is 4.5 per ft² (48.4 per m²), a 6 × 6 is 4.0, a 6 × 9 is 2.67, and a 12 × 12 is 1.0. Multiply by your area, then add cutting waste.

How much sand and gravel base go under a paver patio?

A 1 in (25 mm) screeded bed of washed concrete sand under the pavers, over a compacted aggregate base of 4 in (100 mm) for a patio or 6 in (150 mm) for a residential driveway. The base runs 6 in past the paver edge, so size it to the larger footprint, not the patio itself.

How deep do I excavate for pavers?

Add the layers: paver thickness + 1 in sand + base depth. A 60 mm (2-3/8 in) paver patio on a 4 in base digs to about 7-3/8 in (187 mm); the same paver on a 6 in driveway base digs to about 9-3/8 in (238 mm).

Do I need edge restraint on a paver patio?

On every open side, yes — without it the perimeter pavers creep outward and the field loosens. Spike rigid edging into the base course at about 12 in (305 mm) on center on straight runs, closer on curves. Sides that butt the house or an existing wall are already restrained and need none.

How much extra should I order for cuts?

5% for a straight running-bond or stack pattern on a rectangular patio, 10% or more for a 45° herringbone or a layout with curves and lots of border cuts.