Paver Base Calculator: What Goes Under the Patio
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Patio season in Missouri is set by the subgrade, not the calendar. Clay ground across the north and the west-central plains holds water from late fall into spring and will not compact while it is saturated, so late spring through fall is the stretch when a base actually locks up. The paver base calculator turns that base into tons, and the worked job below shows every number it takes to get there.
A 16 by 20 Patio Off a Walkout, Figured End to End
Hypothetical dimensions. A patio 20 ft along the house and 16 ft out from it, in a pattern of standard 2 3/8 inch pavers.
The paved surface is 320 sq ft, but the base is not the same size. It runs 6 inches past every exposed paver edge so the edge restraint has something solid beneath it, and three sides here are exposed. That makes the base 21 ft by 16.5 ft, which is 346.5 sq ft.
At 4 inches compacted, suitable for foot traffic on firm ground:
- 346.5 x 4 / 12 = 115.5 cu ft
- 115.5 / 27 = 4.28 yd3
- 4.28 x 1.50 = 6.42 tons, or 7.06 with the 10 percent box. Order 7.5 tons.
On the clay subgrade that most of this state's back yards sit on, add 2 inches and a woven geotextile under the stone, which takes it to 6 inches:
- 346.5 x 6 / 12 = 173.25 cu ft, which is 6.42 yd3 and 9.63 tons, or 10.6 with the allowance
The bedding sand sits on top of that at a strict 1 inch: 346.5 / 12 = 28.9 cu ft, which is 1.07 yd3 and 1.44 tons. Excavation is the three layers added up. Four inches of base, one of sand and a 2 3/8 inch paver is 7 3/8 inches below the finished paver height, less whatever reveal you want showing above the lawn. Mark that depth on a stake and check it as you dig, because ground taken out below the line has to be bought back as stone.
Putting the Skirt and the Compacted Depth Into the Paver Base Calculator
Measure the paved shape in feet, add a foot to each dimension that has two exposed edges and half a foot where only one edge is exposed, then enter that larger figure. The form takes a rectangle, a circle, or up to five areas totaled together, which suits a patio with a path leg running off it.
Depth goes in as inches, anywhere from 0.25 to 24, and it is the compacted depth every time: 4 inches under patios and walkways, 6 under cars or over clay, 8 over soft ground. Pick the material, keep the 10 percent box for compaction and spillage ticked, as it is by default, on rough ground, and calculate for cubic yards, tons and cubic feet. The quote can be emailed if you would rather not copy the figures down.
Place the stone in 2 inch lifts with a plate compactor and a light mist on each one, damp rather than wet. Build a fall of about 2 to 3 percent into the finished base running away from the house, because the sand and the pavers will follow whatever grade is underneath them. That fall matters more here than usual: this is a state where a summer storm can drop an inch of rain in an hour and a patio that holds water against a foundation is a problem all year.
Tons at 1.50 to the Yard, and Why the Sand Is 1.35
Cubic yards are base area in square feet times compacted depth in inches divided by 12, all divided by 27. Tons are those yards times the weight per yard.
| Layer | Material | Pounds per cubic yard | Tons per cubic yard |
|---|---|---|---|
| Structural base | Crusher run or base rock | ~3,000 | 1.50 |
| Thin leveling only | Screenings | ~2,900 | 1.45 |
| Bedding, 1 inch | Mason or washed sand | ~2,700 | 1.35 |
At 4 inches compacted, a ton of base stone covers about 54 sq ft. At 6 inches it covers 36, and at 8 inches 27. Doubling the depth halves the coverage, which is why a driveway apron eats so much more stone than the patio beside it. Tons are the ordering figure; cubic yards tell you how much of the drive the pile will occupy before you start moving it.
Digging Twice Costs More Than Half a Ton of Spare Stone
Base stone is the easiest layer in the assembly to get right and the most awkward to put right afterwards, because fixing it means lifting pavers. Round up to the next half ton. Spare base goes under the edge restraint, into the ramp where the path meets the lawn, or into the low corner you find once the string line is up.
Order the stone to arrive after the excavation is dug, not before. A pile sitting on the lawn for two weeks leaves a dead rectangle you then have to repair, and on clay it will also seal the ground underneath it.
Crusher Run Under the Patio, Screenings Only on Top
The structural course is crusher run or base rock, which in Missouri is the dense-graded material specified locally under MoDOT as Type 1 or Type 5. Those are specification names for the material, not a certification held here. Both carry the fines that let a base lock up under a compactor, and both are figured at the same 1.50 tons per yard, so the tonnage above holds whichever you order.
Screenings are a thin leveling layer over a compacted base, never the base itself. On their own they hold water and pump under load. Sand is not a substitute either: deeper sand shifts and the pavers rock. That is why the bedding layer stays at exactly 1 inch and is sized separately on the paver sand calculator. If you are pricing the same stone for a drive or a lane rather than a paver assembly, the crusher run calculator returns the same tonnage without the skirt and excavation arithmetic.
Once the tons are settled, set a quantity and a delivery date on the product page. Delivery is arranged at checkout by ZIP code and the truck needs clear access to the dump spot, so pick somewhere firm and close to the dig. Depth over clay, or a drop that looks tight, is worth raising on the contact page first.
Common questions
The patio runs downhill away from the house. Does the slope change the base tonnage?
Barely, and you should not cut depth to chase it. A 2 to 3 percent fall adds a fraction of a percent to the surface area, which the rounding already covers. Cut the fall into the subgrade so the base stays a consistent 4 or 6 inches thick along its whole length rather than thinning at the low end.
My patio has a path running off one corner. Can I do both at once?
Yes, using multiple areas. Split them where the path meets the patio so nothing is counted twice, and give each its own depth if the path crosses a spot where a car parks. A 21 by 16.5 ft base at 4 inches plus a 4 by 22 ft path base at 4 inches comes to 434.5 sq ft, 144.8 cu ft, 5.36 yd3 and 8.0 tons.
Does the edge restraint sit on the base or on soil?
On the compacted base, which is the whole point of running it 6 inches past the pavers. Spikes driven into lawn soil work loose over a winter of freezing and thawing, and the outside row of pavers then creeps. Include that skirt in the area you enter.
How do I split the order between the base and the layers above it?
Three calculations, not one. Base stone at its compacted depth here, bedding sand at 1 inch on its own page, and joint sand by the bag. Put the stone and the sand on the same order so both are on site before the pavers go down.
My patio front is curved. How do I measure it?
Square it off. Take the overall length and the widest width, add the 6 inch skirt, and enter that rectangle. The extra you calculate along the curve becomes your spare, which beats measuring a segment and finding the base short at the arc. For a circular landing, circle mode and the diameter plus a foot will do it.
Related calculators
The pavers get the compliments. The base earns them.
Crusher run and screenings by the ton, free delivery, ordered together with your bedding sand.