Paver Base Calculator for Patios, Walks and Drives
Enter your project dimensions
Most people arrive at a paver base calculator with a back patio in mind, and on Virginia clay that patio's future is decided by the layer nobody sees. Clay takes water in slowly, holds it, and moves as it wets and dries. Pavers set over a base that is too thin or too small in plan will telegraph all of that within a few freeze-thaw winters. The questions below are the ones in the order they matter, worked through on one patio.
Do I measure the pavers, or the hole they sit in?
The hole. The base has to carry the edge restraint as well as the pavers, so it runs 6 inches past the paving on every open edge.
Take a patio 24 ft by 12 ft off the back of the house, hypothetical dimensions, which is 288 square feet of finished paving. The house closes one long side, so the base extends on the two ends and the one open long side: 24 plus 0.5 plus 0.5 gives 25 ft, and 12 plus 0.5 gives 12.5 ft. That is 312.5 square feet to enter, about 8 per cent more than the paved area. Use rectangle with length and width in feet for that, circle with a diameter for a round seating area, and multiple areas for up to five sections when a patio steps out into a walk.
How deep does the base go over ground that holds water?
Four compacted inches is the figure under a patio or a walkway on ground that drains. Six is the figure over clay, which covers most Piedmont back gardens, and 6 to 8 where cars will stand. On soft or saturated subgrade, add 2 inches and lay woven geotextile underneath so the stone does not work down into the clay through a wet winter.
Two inches is not a base at any point. It is a leveling layer, and pavers set over it move in the first season. Frost depth in Virginia is set by each county or city, from about 12 inches near the coast to about 24 in the northern counties, so anything with a footing needs the local figure rather than a patio rule of thumb. Our example patio sits on clay, so it takes 6 inches.
What does that base weigh once it is converted?
Six inches is half a foot, so 312.5 x 0.5 gives 156.25 cubic feet. Twenty-seven cubic feet make a cubic yard, so that is 5.79 cubic yards. Dense-graded base is published here at about 3,000 lb a cubic yard, or 1.5 tons, so 5.79 x 1.5 comes to 8.68 tons.
The panel returns cubic yards, tons and cubic feet together, and Email my quote sends the three to your inbox. Cubic yards tell you how much of the drive the pile will take. Tons are the ordering unit. Cubic feet are the figure to keep if you are checking a small section by hand later.
Is the 10 per cent box worth leaving ticked on a patio this size?
Leave it ticked here. On 8.68 tons it adds about 0.87 of a ton, bringing the figure to 9.55, and a patio base loses material in three places: the plate compactor squeezing each lift, spillage as wheelbarrows cross a lawn, and the low corner of an excavation that always turns out deeper than the string said. Order 10 tons.
The tick box is on by default and it is the only extra-quantity control on the form, so nothing else has been added to your result. What it will not cover is a subgrade that has gone soft after a wet spell. That belongs in the depth field and under a fabric layer, not in a percentage.
Which stone goes under the pavers, and which does not?
21A is the base. It carries the fines that let it lock up hard under a plate compactor, which is exactly what the structural layer needs. 21B is the coarser, lower-fines size and the site's crusher run product; it drains a little more freely and packs a little less tightly, and it is a reasonable base where the ground is already free-draining.
Screenings are not a base. Used alone under pavers they hold water and shift under load, and their place is a thin leveling skim over compacted stone. Clean drainage stone such as #57 is not a base either, since it stays loose by design.
How deep do I dig before any of this goes in?
Add the layers and subtract the reveal. Our 6-inch base, 1 inch of bedding sand and a standard 2 3/8 inch paver come to 9 3/8 inches below the finished paver surface, less however much you want the patio standing proud of the lawn. Set a stake with the depth marked on it and check as you dig, because going too deep costs twice: once in soil to shift, and again in stone to bring the grade back. The soil leaving the excavation has to go somewhere as well.
Place the base in 2-inch lifts, mist each one, and compact it. Give the finished base a fall of 2 to 3 per cent away from the house; the bedding and the pavers copy whatever the base does. Bedding sand is a separate fixed 1-inch layer at about 2,700 lb a cubic yard, and on this footprint that is 0.96 of a yard, or 1.30 tons. Size it on the paver sand calculator, order mason sand for the bedding inch, and put both materials on one delivery, arranging the drop by ZIP at checkout.
Common questions
I am lifting an old patio and relaying it. Do I need a full base again?
Only if the old one has failed. Pull the pavers, sweep off the old bedding sand and look at the stone: if it is flat, firm and dry after rain, it can stay, and you are ordering a fresh inch of bedding sand rather than tons of base. Where there are dips, soft spots or standing water, take it out, because a bad base recreates the same patio under new pavers.
What happens if the base order comes up short?
You either thin the layer to stretch it, which is the failure the whole page is about, or you leave an open excavation across a stretch of Virginia weather while a second load is arranged. On clay, an open hole after two days of rain has to be dried or dug out before work restarts, so round the tonnage up rather than down.
How accurate is this against what the patio actually takes?
The arithmetic is exact for the dimensions you enter. The real variance sits in the excavation floor, which is never as flat as the string line suggests, and in how hard you compact. A base dug by hand over clay commonly absorbs a little more than the calculation, which is the case for leaving the extra 10 per cent ticked.
Which listing do I open once the tonnage is settled?
21A for the structural layer, and mason or washed sand for the bedding inch. If the ground is naturally free-draining and you would rather have the coarser size, 21B carries the same weight per yard, so the tonnage transfers without recalculating.
Where should the load go while the excavation is open?
Pick the drop spot before you order. The truck needs clear access and room to raise its bed, with nothing overhead, and the pile wants to be on the drive rather than the lawn, close to the work and not on the side you will be wheelbarrowing across. Stone left standing on grass for two weeks leaves a dead patch the shape of the pile.
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.