Paver Base Calculator

Enter your dimensions above and the calculator returns the answer in the units suppliers actually sell in — cubic yards, cubic feet, tons and bags.

Typical paver base depth by application

Paver base is crushed stone with fines — often sold as 3/4 inch minus or road base — that compacts into a stable, semi-locked layer under the bedding sand.

What the numbers assume

The result uses a bulk density of 105 lb per cubic foot and a default waste allowance of 10%. Both are typical values, not measurements of your material — bagged products and different aggregate sources vary by 10% or more. Change the waste field if your subgrade is uneven or you are pouring against forms with complex edges.

Base must be compacted in 2-inch lifts with a plate compactor and watered as you go. Dumping 4 inches at once and running a compactor over the top leaves the bottom loose and the pavers sink.

Costs shown are material only, based on a national average price you can edit. They exclude delivery, short-form fees, equipment rental and labour.

A paver patio is two structures stacked on top of each other, and almost every failed patio failed in the bottom one. The pavers are the wearing course — they take the abrasion and the point loads from a chair leg, and spread the load across their footprint. Everything below them carries it to the ground. When a patio develops ruts along the driveway edge, settles in the middle, or rocks on a spring morning, the pavers are almost never the cause.

The base is the structure

Compacted crushed base with fines behaves, once properly compacted, like a weak but genuinely rigid slab. It spreads a wheel load over an area several times the size of the tyre contact patch, and it resists the horizontal forces that try to push the pavers outward.

Bedding sand and pavers do none of that. Sand has essentially no shear strength once loose, and a paver is a brittle plate. Stack them on soft subgrade and the assembly does not stiffen — it transfers the deflection upward, which shows up as a dip, a rock, or a joint that opens. Depth is therefore a load question, not an area question: the base does not get deeper because the patio is bigger, it gets deeper because heavier things drive on it.

Why clean gravel never locks up

The most consequential ingredient decision is fines.

Paver base — sold as ¾ inch minus, road base, or crushed stone with stone dust — contains everything from ¾ inch stone down to dust. When you compact it, the water you add lets the particles slide into a denser arrangement and the fine material fills the voids between the larger stones. The result is a semi-locked matrix that resists movement in every direction.

Clean gravel — washed stone, drain rock, pea gravel — has had those fines removed. It compacts a little but never locks. Under a paver the layer keeps shifting, the pavers move with it, and the joints open. Clean stone also drains beautifully, which is why it is the right product in a French drain and the wrong product under a patio. The gravel calculator covers the clean-stone side of that split; this page is about the side with dust in it.

If your supplier cannot tell you whether a product has fines, squeeze a handful. Base material feels like sharp chips blended with grit that stains your palm; clean stone leaves your hand dusty at most.

Compaction: two-inch lifts, or don't bother

Base that is dumped and compacted from the top is not compacted. It is a pile with a hard crust. A plate compactor transmits its energy through the top few inches, so a 4-inch layer placed at once stays loose underneath. The surface feels hard enough to fool you. Then traffic works the loose bottom layer, the crust above cracks and settles, and the pavers follow.

The method that works:

• Place in 2-inch loose lifts, one at a time.
• Water each lift lightly before compacting — damp, not saturated. A cloud of dust means the material is too dry to compact.
• Run the plate compactor over each lift in overlapping passes, at least two full passes in each direction.
• Compact the subgrade before you start and check the slope. Base corrects nothing.

The audio check is the one experienced installers use. A properly compacted lift rings under the plate — a hard, slightly hollow note. A loose lift thuds and the plate sinks. If it thuds, keep going; if it still thuds after several passes, the material is too dry or the lift too thick. No hand tamper gets there; this is one rental where the difference is structural.

The 4 / 6 / 8 ladder

Depth follows the heaviest thing that will regularly cross the surface, not the average.

Two notes matter more than the table. First, soft subgrade can cost you a step: on clay or uncompacted fill, 4 inches of base on a walkway will move underfoot. Excavate deeper, compact the subgrade, and consider a woven geotextile so the base does not migrate downward. Second, frost depth is set locally and overrides all of this. Check with your local building department rather than relying on a national average.

Edge restraint and drainage: the two things that decide

A paver field is a set of loose units sitting on sand, held only because the outer course is restrained and the water underneath has somewhere to go.

Edge restraint is what converts a pile of pavers into a surface. Without it, the outer courses creep outward under repeated loading and the pavers at the edge walk off the base within a couple of seasons. Use a rigid restraint — a concrete curb, or an aluminium or plastic edging profile spiked through the base into the subgrade. Garden edging pushed into sand does nothing.

Drainage stops the base becoming a bathtub. Slope the base itself at 1–2%, not just the pavers, and intercept water arriving from uphill — if the patio sits below a slope, that water needs a swale or a French drain. Trapped water softens the subgrade, and a softened subgrade fails no matter how much stone sits on top.

The bedding layer is a separate order

The bedding layer is 1 inch of coarse, sharp masonry sand on top of the finished base, screeded flat and left loose. The pavers are pressed into it, so each paver gets full contact and load spreads evenly into the base instead of concentrating under one corner. Build the slope into the base, never into the bedding: correcting grade there means uneven bedding thickness — the same failure as over-thick bedding, covered in the sand calculator.

Do not use polymeric sand as bedding. It is a joint material, swept into the gaps and cured after the pavers are laid, and it will not support a paver.

Worked example: a 12 × 12 patio

Take a 144 ft² patio at 4 inches compacted, the standard foot-traffic build-up.

144 ft² × 0.333 ft  = 48.0 ft³
48.0 ft³ ÷ 27       = 1.78 yd³        compacted, in place

Crushed base compacts around 20%, so you have to buy the loose volume that will become 1.78 yd³ in place:

1.78 yd³ ÷ 0.80     = 2.23 yd³        loose, before waste
2.23 yd³ × 1.10     = 2.45 yd³        with the 10% waste allowance

The job is roughly 2.4 to 2.5 yards of loose ¾ inch minus — the 1.78 nominal figure is not what you order. At 105 lb per cubic foot that is about 2.4 tons, which is why this arrives on a truck. The default price is around $48 per cubic yard as a US national average for material only, and it is really a quarry-plus-freight number. Type your own supplier's figure into the price field, and let the methodology page tell you where the rest of the defaults come from. If your project mixes base, bedding and a hard surface, the material calculator keeps the layers from getting confused with each other.

Build the bottom layer first

It is tempting to treat the base as the invisible chore you rush through to reach the pavers, and that instinct is backwards. The pavers are the part you can replace in a weekend with a pry bar and a wheelbarrow of sand; the base is the part you cannot fix without tearing the whole patio out.

So spend your effort where it gets buried. Excavate deeper than you think you need to, compact the subgrade, buy stone with fines, place it in 2-inch lifts, water each one, run the plate until the surface rings, and check the slope before you screed a single grain of bedding sand. Then restrain the edges and give the water somewhere to go. Do those things and the pavers become almost irrelevant, which is the highest compliment a wearing course can receive. Skip them and no paver on the market will save you.