Gravel & aggregate
How Much Gravel Do You Need Under a Patio?
By the HomeCalc USAReviewed against our editorial policyLast updated US units and pricing
A paver patio typically needs 4 to 6 inches of compacted crushed-stone base — 4 inches over well-drained sandy soil, 6 inches or more over clay — plus a 1-inch bed of coarse sand for setting the pavers. A 12 ft × 12 ft patio at 6 inches needs about 2.7 cubic yards, roughly 3.8 tons of crushed stone.
Skip the arithmetic: use the Gravel Calculator.
Quick answers on yards, tons and depth: read the Gravel FAQ.
Key takeaways
- Base depth depends on soil: 4 inches over free-draining sand, 6-8 inches over clay or where frost heave is a factor.
- Compact the base in 2-3 inch lifts — one thick loose layer never reaches full density.
- The 1-inch sand bed under pavers is bedding sand, not part of the gravel order; it is bought separately by the bag or yard.
- A loose gravel patio with no pavers needs only 2-3 inches of surface stone over fabric.
Two kinds of gravel patio
The phrase covers two very different builds. A paver patio uses gravel only as a hidden structural base under concrete or stone pavers. A loose gravel patio uses gravel as the finished surface itself. The quantities differ a lot, so decide which you are building before ordering.
For pavers, the gravel never shows and its job is purely structural: spread load, drain water, and resist frost. For a loose gravel surface, the stone is the patio, and comfort and appearance drive the choice — typically 3/8-inch angular chip or decomposed granite over fabric.
Base depth by soil type
These figures assume the base is compacted in lifts of 2 to 3 inches with a plate compactor, each layer wetted lightly and passed several times before the next goes down.
Recommended compacted base depth for a paver patio in US conditions.
| Soil under the patio | Compacted base depth | Why |
|---|---|---|
| Sandy, free-draining | 4 in | Drains fast, little frost movement |
| Loam or mixed | 6 in | Moderate drainage and frost risk |
| Heavy clay | 6 – 8 in | Holds water; frost heave risk |
| Cold climates (deep frost) | 8 – 12 in | Base should approach local frost depth |
Calculate the base quantity
- Measure the patio length and width in feet, adding 6 inches all round — the base should extend past the pavers.
- Convert base depth to feet: 6 inches ÷ 12 = 0.5 feet.
- Multiply for cubic feet and divide by 27 for cubic yards.
- Multiply by 1.4 for tons of crushed stone and add 10% for compaction.
Worked example
A 12 ft × 12 ft paver patio over clay, base extended to 13 ft × 13 ft at 6 inches: 13 × 13 × 0.5 = 84.5 cubic feet, which is 3.13 cubic yards, or about 4.4 tons of 3/4-inch crushed stone with a 10% allowance. Add roughly 0.4 cubic yards of coarse bedding sand for the 1-inch setting bed — about twelve 50 lb bags.
For the same footprint as a loose gravel patio at 3 inches of surface stone, the order drops to about 1.6 cubic yards — less than half.
Common base mistakes
- Skipping compaction between lifts, which leaves a soft core that settles unevenly within a year.
- Using rounded drainage stone as a base — it never locks. Base material must be angular crusher run with fines.
- Forgetting slope: the finished patio should fall about 1/4 inch per foot away from the house.
- Laying pavers directly on stone dust without a proper crushed-stone base beneath it.
Frequently asked questions
Can I lay pavers on gravel without sand?
You can set pavers on a 1-inch bed of coarse sand or on stone screenings, but not directly on open-graded gravel — the voids let pavers rock and sink. The gravel provides the structural base; the thin sand or screening layer is what the pavers actually sit on.
How many tons of gravel for a 12x12 patio base?
At a 6-inch compacted depth with the base extended 6 inches past the edges, about 4 to 4.5 tons of 3/4-inch crushed stone, including a 10% compaction allowance. A 4-inch base over sandy soil needs around 3 tons.
Is crusher run or clean stone better for a patio base?
Crusher run (crushed stone with fines) compacts into a firm, stable layer and is the standard base choice. Clean, open-graded stone drains better but does not lock together; it is used where drainage is the priority, usually with a geotextile separator and extra care in compaction.
Sources and references
- NRMCA — aggregates in construction — Aggregate types and construction uses.