Paver Base Calculator: Sizing the Stone Under a Patio on Sand
Enter your project dimensions
The real decision in front of you is not which paver to buy. It is how many inches of compacted rock go underneath it, because on loose sand that number is the only thing holding the surface flat once a rainy season has been through it. This paver base calculator turns the inches you settle on into cubic yards and tons. What it cannot do is decide the inches for you, and it is worth being honest about the rest of what it cannot see.
What a tonnage figure cannot tell you about the sand under a patio
The tool works from a footprint and a depth. It does not know that the first eight inches of your yard are organic sand that has to come out before anything is compacted, or that a flatwoods lot may have a hardpan sitting a foot or two down that perches water above it after a storm. It does not know whether the low end of the patio drains away from the house or toward it. It cannot see a soft muck pocket left where a tree was taken out years ago, and on ground like that a soft spot will telegraph through a patio no matter how good the arithmetic was.
So treat the figure as the material order, not the design. Walk the area the day after heavy rain and see where water stands. Dig a test hole at the low corner. Then come back and enter a depth you can defend.
Compacted inches, cubic yards and the 1.5 tons behind each one
Base is sold by weight and specified by thickness, so three units have to line up. Multiply your base area in square feet by the depth in inches and divide by 12, and you have cubic feet. Divide by 27 for cubic yards, because a yard is a three-foot cube. Multiply the yards by the published weight of the material for the tons line.
Limerock Base and Crusher Run are both published on this site at roughly 3,000 lb a cubic yard, which is 1.50 tons. Limerock is the standard base rock here, crushed limestone graded down to fines that lock together and set up hard over sand. A yard of it is not quite a ton and a half, and a small patio takes less than most people expect, which is exactly why guessing produces a half-load short.
Enter the compacted thickness, not the loose pile height. Material spread to four inches loose will finish under four once the plate compactor has been across it.
Where the paver base calculator wants the six inches past the pavers
The footprint you enter is not the paved area. Carry the base six inches beyond every open edge, so the edge restraint sits on compacted rock instead of sand. Skip that and the outer course of pavers creeps outward, which is the failure you see on half the older patios in a neighborhood.
Then pick your depth. Four inches compacted under a patio, walk or seating area. Six to eight under anything cars stand on. Add two inches where you are building over soft or freshly stripped sand, and put woven geotextile down first so the stone is not slowly pushed into the subgrade during the wet season.
The tool itself takes Rectangle, Circle or Multiple areas with up to five pieces, lengths and diameters in feet, depth in inches from a quarter inch to 24. A material select sets the weight, and a checkbox, ticked by default, adds 10 percent for compaction and spillage and can be unticked. Results come back as cubic yards, tons and cubic feet, and can be emailed to you.
One more figure comes out of the depth you chose. Excavation depth is base plus one inch of bedding plus the paver thickness, less whatever reveal you want above the lawn. Four inches of base, one inch of bedding and a paver of two and three eighths inches puts you around seven and a half inches below the finished surface. Mark that on a stake and check it while you dig, because over-digging costs you twice: hauling spoil out and buying stone to bring the grade back.
A small back patio and a paver apron at the end of the drive
Both hypothetical, both worth following through.
A patio 14 feet out from the house by 11 feet along it has three open edges. Add six inches to the free end and to each side, and the base area becomes 14.5 by 12 feet, which is 174 square feet, not the 154 you paved. At four inches compacted, 174 x 4 = 696, divided by 12 is 58 cubic feet, divided by 27 is 2.15 cubic yards. At 1.50 tons a yard that is 3.22 tons, or 3.54 with the 10 percent ticked. Four tons.
A paver apron at the end of the drive, 20 by 12 feet with all four edges open, becomes 21 by 13 feet, which is 273 square feet. Over stripped sand it gets seven inches. 273 x 7 = 1,911, divided by 12 is 159.25 cubic feet, divided by 27 is 5.90 cubic yards, or 8.85 tons, and 9.74 with the allowance. Call it ten tons.
Note what changed. The apron is less than twice the paved area of the patio and takes nearly three times the stone, because depth does the heavy lifting.
Buying the extra in stone, never in bedding sand
When the number comes out between two round figures, round up on the stone. Base is the layer you cannot add to later without lifting everything, and half a ton spare compacts into a thin spot or fills the wheel ruts the wheelbarrow leaves in the lawn.
What you must not do is make up a shortfall with bedding sand. Sand stays at one screeded inch whatever the base does, and a deep sand bed over a thin base moves under load until the pavers rock. Size that inch on the paver sand calculator, which handles bedding and joint fill as two different quantities.
Place the base in two-inch lifts, mist each one lightly, and finish with a fall of two to three percent away from the house so the storm that arrives while the pavers are half laid runs off rather than ponding. A drive being built in rock instead of pavers is a different depth conversation and belongs on the crusher run calculator.
Once the tonnage looks right, open the product page to choose a quantity and a date, or ask through the contact page if the test hole turned up something you did not expect. If you are still weighing surfaces, everything sold by the ton is in one list.
Common questions
Does the six-inch overhang go on the side against the house too?
No. Carry it past open edges only, the ones where an edge restraint or a spade-cut edge will hold the pavers in. Against a slab, a wall or an existing footing there is nothing to restrain, so measure to the face of it. On a three-sided patio that means adding half a foot to one dimension and a full foot to the other.
How do I order the base and the bedding sand in one go?
Calculate them separately, because they are different materials at different depths and different weights. Base is your full compacted depth over the extended footprint at 1.50 tons a yard. Bedding is exactly one inch of coarse sand over the same extended footprint at 1.35 tons a yard. Order both lines together and have them dropped as two piles.
The patio has a curved front edge. What do I put in the length and width boxes?
Enter the rectangle that contains the curve and let the extra tonnage be your margin, or split the shape under Multiple areas into a rectangle plus a circle segment you approximate with a second rectangle. On base material, rounding outward is the cheap error.
I am lifting an old patio and resetting it. Do I need the full tonnage again?
Probably not. Strip the pavers and the old bedding sand, then test the base: if it is level, firm underfoot and not holding water, it may only need a fresh inch of bedding and a little stone in the dips. Where you find depressions, soft ground or standing water, take it out and rebuild, because a failed base under new pavers fails again the same way.
What happens if I order too little base?
You either spread it thinner than you planned or stop halfway and wait. Both are worse than the alternative. A base compacted at two inches is a leveling course, not a base, and four compacted inches is the floor for foot traffic. If the figure lands awkwardly between two amounts, order the larger one.
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.