One inch is standard. More than that invites rutting.
Crushed stone loses roughly a quarter of its loose volume once compacted.
An estimate only. Required base depth depends on your soil type, drainage and local frost depth. Clay soils and cold climates need more. Ask your supplier what they recommend for your area before ordering.
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How to use it
Measure the area
Length times width in feet. For an irregular shape, break it into rectangles and add them.
Pick the use
Four inches for a patio, six to eight for anything a vehicle drives on.
Order loose, not compacted
Crushed stone loses about a quarter of its volume once compacted. The result allows for that.
How the calculation works
The base volume is area times depth, converted to cubic yards. The compaction allowance is added on top, because suppliers sell loose material while you are specifying a compacted depth.
Twenty-five percent is standard for crushed stone. Skip it and you finish a quarter short, which is the most common ordering mistake on a patio project and usually means paying a second delivery charge.
The excavation depth shown is the sum of three layers: compacted base, bedding sand, and the paver itself. The calculator assumes a 2 3/8 inch paver. If yours is thicker, dig deeper by the difference.
What this calculator does not do
It does not know your soil. Clay holds water and needs a deeper base than sandy soil. If your ground stays soft for days after rain, add two inches.
It does not account for slope. A patio needs a fall of about one eighth of an inch per foot to drain away from the house.
It cannot tell you whether you need geotextile fabric. On soft or clay soils it stops the base sinking into the subsoil, and it is cheap insurance.
Questions
How deep should a paver base be?
Four inches compacted for a patio or walkway. Six to eight if a car drives on it, more in cold climates.
Can I use sand instead of stone?
No. Sand under the whole base shifts and ruts. Sand belongs in the one inch bedding layer only.
What stone should I ask for?
Crushed angular stone, sold as crusher run, road base or 3/4 inch minus. Avoid rounded pea gravel, which never locks together.
Do I compact in layers?
Yes, in lifts of two to three inches. A single thick lift never compacts all the way down and the patio settles a year later.
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