Paver Base Calculator: The Base Is Wider Than the Patio

Nine orders in ten come up short for the same reason: the patio was measured, and the base was not. Stone has to run 6 inches past every exposed paver edge so the edge restraint has something solid to sit on, and on a small Maryland patio that band alone is a tenth of the order. The paver base calculator works from whatever area you give it, so the measuring is the part that decides whether the figure is right.

The band past every exposed edge, and the shapes that hide it

Start with the paved outline, then grow it. Each side that ends in open ground gains 6 inches; the side that runs up against the house gains nothing.

A patio 18 feet along the back wall and 12 feet out has three exposed sides, so the base rectangle is 19 by 12.5 feet. That is 237.5 square feet against 216 of paving, and the difference is real stone.

Awkward outlines break into pieces rather than being averaged.

• A curved front edge goes in as a rectangle to the narrowest point plus a circle for the bulge, with the circle halved by hand.
• Steps down to a lawn are their own small rectangle, because the landing under them is base too.
• An L around a bump-out is two rectangles that share no overlap, entered under the multiple-areas option, which holds up to five.
• A path meeting a patio is a separate run at its own depth, not part of the same rectangle.

Measure to the outside of the base band each time, not to the paving.

Putting a base area, not a patio area, into the form

Shape first: rectangle, circle, or multiple areas for up to five at once. Lengths and widths go in as feet, and circle mode asks for the diameter straight across the widest point.

Depth is entered in inches and the form takes anything from 0.25 to 24. Use the compacted figure you want under the pavers, not the height of the loose pile. Choose the material next, because that selection sets the weight the tool converts with, and leave the box for 10 percent extra covering compaction and spillage ticked, or untick it. Cubic yards, tons and cubic feet all come back together, and the result can be emailed across as a written quote.

Running the 18 by 12 patio through it at 4 inches: 237.5 square feet by a third of a foot gives 79.2 cubic feet, which is 2.93 cubic yards, or about 4.40 tons at roughly 1.50 tons per cubic yard. With the 10 percent box ticked it reads 3.22 cubic yards and about 4.84 tons, so the order rounds to 5 tons. That patio is invented for this page, as are the two below.

Four inches under a garden chair, eight over soft Shore ground

Depth is where the Maryland subgrade gets a say.

Central Maryland silt and clay loam turn soft and hard to compact when saturated, and fabric under the base keeps stone from pressing down into it through a wet spring. Low, flat Coastal Plain ground near the Bay and the tidal rivers sheds water slowly for the same reason, which is what puts an apron on the Shore at the 8-inch line rather than the 6.

One local check before any of this. The Chesapeake and Atlantic Coastal Bays Critical Area runs 1,000 feet back from tidal waters and tidal wetlands, and lot coverage there counts gravel, stone, shell, pavers and permeable pavement. The cap is 15 percent in a Limited Development Area and tighter in a Resource Conservation Area. Your county's Critical Area program administers it, so check with them first.

Reading the result against a seven and a half inch dig

Three figures come back and each answers a different question.

Cubic yards is the volume of the hole you are about to make. Tons is the ordering unit for this material, so that is the figure that goes on the listing. Cubic feet is the one to keep for small additions, like the strip under a step.

The dig itself is an addition the form does not do for you. Add the base depth, 1 inch of bedding sand and the paver thickness, then take off however much you want the finished surface standing above the lawn. A standard 2 3/8 inch paver on a 4-inch base works out at 7 3/8 inches, and marking seven and a half on a stake is close enough to dig to. Set that stake before the spade goes in, because digging too deep means hauling soil out and then buying stone to put the level back.

An Eastern Shore apron and a 44-foot garden path

A parking apron, 20 by 12 feet, exposed on three sides. The base area is 21 by 12.5 feet, or 262.5 square feet. On soft Shore ground that wants 8 inches, so 262.5 by two thirds of a foot is 175 cubic feet, which is 6.48 cubic yards, or about 9.72 tons. With the 10 percent allowance, 10.7 tons.

A garden path, 3 feet wide and 44 feet long, exposed both sides and both ends. The base runs 4 feet wide and 45 feet long, which is 180 square feet. At 4 inches that is 60 cubic feet, 2.22 cubic yards, or roughly 3.33 tons. With the allowance, 3.7 tons.

Two jobs on the same property, and the apron takes three times the stone for a footprint half again as large. Depth does that, not area.

Ordering the stone and the sand as two separate lines

Three tools cover a paver build and each has its own job.

• This page sizes the structural course. Buy it as Crusher Run or as CR-6, the dense-graded base Maryland yards specify, both of which convert at the same published weight.
• The paver sand calculator handles the bedding layer, fixed at exactly 1 inch and converted at a lighter figure. Do not make up base depth with extra sand, because a deep sand bed shifts and the surface rocks.
• The crusher run calculator is the one for the same material outside a paver job, a shed pad or a lane, where there is no overhang band to add.

Screenings, or stone dust as Maryland yards say it, belong as a thin leveling skim over a compacted base and nowhere else in the stack. On their own they hold water and shift under load.

Place the base in 2-inch lifts, mist each lift lightly before the plate compactor goes over it, and give the finished surface a 2 to 3 percent fall away from the house before screeding. Edge restraint pins into the compacted base, which is what the 6-inch band was for. Set a delivery date on the listing, since delivery is arranged at checkout by ZIP code, and the delivery page covers what the truck needs at the drop. Have the material dropped after the dig rather than before.

Common questions

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