Paver Calculator

How to estimate pavers, sand and base

A patio is three materials stacked, and only the top one is the thing people count. The pavers are a division. The sand and the stone underneath are volumes, and the base is the part nobody publishes a number for.

paver face (sq ft) = length (in) × width (in) ÷ 144
pavers = patio area ÷ paver face, then + cut allowance
bedding sand (cu ft) = area × 1 in ÷ 12Bedding depth is Pavestone's own CSI specification: screed to a nominal 1 in, not exceeding 1-1/2 in.

Do not round the paver before you divide

This is the one that costs money, and it is easy to walk into.

A 4 by 8 inch paver has a face of 32 square inches. Divided by 144 that is 0.2222 square feet. Round it to 0.23 for tidiness, divide a 600 square foot patio by that, and you get 2,609 pavers. Carry the unrounded figure and you get 2,700.

Ninety-one pavers, a 3.4 percent shortfall, and it does not announce itself. You find it at the far end of the last course, which is the worst place and usually a second trip. This page divides by the unrounded number, and the line-by-line table prints the face area to four decimals so you can see it.

Measure a real paver too. A nominal 4 by 8 is very often 3-7/8 by 7-7/8, which is 4.72 per square foot rather than 4.5. On 120 square feet that is 567 pavers against 540, so 27 more than the name implies.

The cut allowance

Every paver that meets a curve, a wall or a step gets cut from a whole one, and the offcut is rarely usable. That is what the allowance covers, and the right figure follows the pattern rather than the size of the job.

Five percent suits a plain rectangle laid in a running bond, where only the ends of alternate courses are cut. Ten percent is the sensible default for most patios. Twenty is right for herringbone or anything laid on the diagonal, where nearly every perimeter piece is a cut and many are cut twice.

These are estimating conventions and this page labels them as such. No manufacturer publishes a waste factor, because it depends on a shape they cannot see.

One reason to keep the spares rather than return them: dye lots move between production batches. A paver bought a year from now to replace a cracked one will be close, and close is very visible in a field of identical units.

The inch of sand, and what it is not

The specification is unusually precise here, so this page follows it exactly. Spread the bedding sand over the compacted base and screed it to a nominal 1 inch, not exceeding 1-1/2 inches.

The important word is screed. It is a bedding course of even thickness, and the same specification says plainly not to use it to fill depressions in the base. Sand that varies in depth compacts by different amounts under the same load, which is how a patio ends up with dips a year later. Get the base flat, then lay a consistent inch on top of it.

It also rules out materials by name: not mason sand, and not limestone screenings or stone dust. Coarse concrete sand is what the bed is for.

On 120 square feet, an inch of sand is 10 cubic feet, which is about 20 bags at the common half-cubic-foot size, or a third of a cubic yard loose.

The base, and why there is no number for it

You will find plenty of sites quoting a base depth as though it were a published figure. It is not, and the reason is visible in the specification itself: the aggregate base is left as a blank to be filled in per project.

What decides it is your ground. Four inches of compacted crushed stone is common under a patio that only gets walked on, sitting on soil that drains. Poor or clay soil wants more, and so does anywhere the ground freezes deeply. Anything a car drives on is a different question and a thicker build.

Two things matter more than the number. Compact it in layers rather than all at once, because a plate compactor only reaches so far down. And use crushed angular stone, which locks together under compaction, rather than rounded pea gravel, which never does.

The volume is straightforward once you have picked a depth: area times depth in feet, divided by 27 for cubic yards. At 4 inches, 120 square feet needs 40 cubic feet, which is 1.48 cubic yards. Order it by the yard, not the bag.

Edge restraint is not optional

The perimeter figure on this page is the length of edging you need, and it is the cheapest part of the job to get wrong.

Pavers hold together by friction between units. The outer course has nothing on one side, so without a restraint it creeps outward under load, the joints open, the sand washes out and the field loosens from the edge inward. A patio that "spread" did not settle; it was never edged.

A quick cost check

The 12 by 10 patio, 4 by 8 pavers, 10 percent allowance: 594 pavers at about $1 each is $594. Ten cubic feet of bedding sand is roughly 20 bags at $5, so $100. A yard and a half of base is maybe $60 delivered. Forty-four feet of edge restraint runs about $90. Call it $844 before the compactor rental.

Switching to 12 by 12 pavers drops the count to 132 for the same patio, but the price per unit is higher, so compare per square foot rather than per paver.

Common estimating mistakes

• Rounding the paver's face area before dividing. The single most expensive habit on this page.
• Trusting the nominal size. A "4 by 8" is often 3-7/8 by 7-7/8. Measure one.
• Using the same allowance for every pattern. Herringbone cuts far more perimeter pieces than a running bond.
• Treating the sand bed as a leveling layer. It is a screeded inch, and the specification says so.
• Buying a published base depth. There isn't one. It follows your soil.
• Skipping the edge restraint. The patio spreads from the outside in.

When to hand it off

Laying pavers is patient work rather than skilled work, and the measuring on this page is most of the planning. The parts worth thinking twice about are underneath and around it.

Drainage is the real one. A patio needs to shed water away from the house, and if the ground already holds water, more stone on top of it is not the fix. Grading and drainage are their own trade, and getting them wrong shows up as heave, dips and a wet basement rather than as a paving problem.

The other is anything retaining soil. A patio that needs a wall to hold ground back at its edge has stopped being a paving job: past roughly four feet, a retaining wall is an engineering question with real consequences, and no quantity on this page speaks to it.