Paver calculator

A paver patio is three materials: the pavers, a compacted gravel base (at least 4 in under a patio, per ICPI) that runs a few inches past the edges, and about 1 in of bedding sand.

How the paver calculation works

Divide the patio area by the face area of one paver, then add extra for cuts. The laying pattern sets that extra unless you type your own: 5% for straight rows, about 10% for 90° herringbone or when you’re not sure yet, 15% for 45° herringbone, diagonals and curves. Pavers with spacer nubs are sized so their nominal dimensions already include the joint, so no separate joint allowance is needed for most concrete pavers.

pavers = patio area ÷ (paver length × paver width) × (1 + extra for the pattern)
base area = patio + the overbuild on every side (rectangle: (L + 2 × overbuild) × (W + 2 × overbuild))
base tons = base area × compacted depth × compaction factor × (1 + waste) × loose density
bedding sand = patio area × 1 in × 1.1
joint sand = area × joint width × (paver thickness − 1/8 in) × (L + W) ÷ (L × W) × 100 lb/cu ft

Worked examples with every quantity filled in: How many pavers for a 10×10 patio in 4 × 8 in brick pavers, How many 16×16 pavers for a 12×12 patio, How many pavers for a 12×16 patio in 6 × 9 in pavers, and the metric How many pavers for a 3 × 4 m patio.

Base and sand

The gravel base does the real work: it spreads the load and drains water. ICPI (the paver industry’s technical institute) calls for at least 4 in after compaction under a patio on well-drained soil and 6 in under a driveway, with another 2–4 in on wet or weak soil and in cold climates. Oregon State University Extension’s paver guide and Belgard’s installation guidelines both say 4–6 in for a patio. Compact it in two or three thin layers rather than one thick one.

Two things make the base bigger than people expect. First, it runs past the edge of the pavers — the overbuild. ICPI’s guide specification wants the base to reach at least its own thickness beyond the edging spikes (10 in is plenty), so the edge restraint sits on solid stone instead of the lawn. A 12 × 12 ft patio on a 4 in base is really a 12⅔ × 12⅔ ft base. Second, crushed base packs down: dense-graded base (crusher run, DGA) loses 20–30% of its loose volume when you compact it, so you order about 1.25 times the compacted volume. Clean stone like #57 settles only 5–10%. The calculator applies both, then adds 5% for low spots and spills.

The bedding layer is about 1 in of coarse concrete sand, screeded flat; ICPI’s bedding-sand spec keeps it between 1 and 1½ in loose. Don’t use it to fix a lumpy base — thick sand shifts over time and the pavers follow. The calculator adds 10% for screeding and spills. Joint sand is separate: polymeric sand fills the gaps between pavers to about 1/8 in below the top, and small pavers have far more joint per square foot than big slabs.

Dig depth is the three layers stacked: base + sand + paver thickness. With a 4 in base, 1 in of sand and standard 2⅜ in pavers, that is about 7⅜ in below the finished surface — call it 7½ in — before you add the slope away from the house. In the strip where the base runs past the pavers, only the base depth leaves the site, because soil or sod goes back over it; along a side against the house, the base doesn’t run past at all.

Tips

• Slope the finished surface about ¼ in per foot (2%) away from the house, and never less than about 3/16 in per foot (1.5%).
• Order pavers from one production lot if you can, so the color matches.
• Install an edge restraint along every side that isn’t against the house or a slab; without it, the edges creep outward. Snap Edge’s spec prefers 10 in spikes about 12 in apart; closer on curves.
• Building a driveway? ICPI allows 2⅜ in (60 mm) pavers on a home driveway, but many makers suggest 3⅛ in (80 mm), and the base goes to 6 in or more.
• Call your utility locate service (811 in the US) before you dig.

Full walkthrough: how to lay a paver patio. New to the words? Words you’ll hear at the yard explains crusher run, compaction and edge restraint.