Crushed Stone Calculator
Work out how much crushed stone you need for a patio base, path or drainage trench, in cubic yards, tons and cost. The calculator starts with a typical base depth and weight.
What crushed stone is used for
Crushed stone is rock broken into angular pieces. The sharp edges lock together when the stone is compacted, which makes a firm layer that still drains. That is why it is the usual base under pavers, patios and walkways, and a common fill for drainage trenches and gravel driveways.
The calculation is area times depth, the same as any gravel job. If you are not sure the stone is the right material, the gravel calculator covers the general case.
How deep should the base be?
Suppliers and paving guides commonly suggest a compacted base of around 4 to 6 inches under a paver patio or walkway. Going toward 6 inches or deeper is common on soft or clay soil, and in places where the ground freezes and thaws. Driveways need more, often laid in several layers. These are common starting points. Your soil, climate and the loads involved decide the right depth.
| Use | Common compacted depth |
|---|---|
| Paver patio or walkway, stable soil | about 4 inches |
| Soft, clay or freeze-thaw ground | about 6 inches or more |
| Driveway | thicker, often in layers |
Compaction changes how much you buy
Crushed stone is spread loose and then compacted, and a compacted layer is thinner than the loose one you started with. If you only order the finished volume, you can come up short. Add an allowance in the extra field, and if the job is a deep base that will be compacted hard, talk to your supplier about how much more to order.
How far does a ton go?
At 1.4 tons per cubic yard, one ton is about 19 cubic feet. That covers roughly:
| Depth | Area per ton |
|---|---|
| 4 inches | 58 sq ft |
| 6 inches | 39 sq ft |
Worked example
A patio base 12 ft by 12 ft and 4 inches deep, with 10 percent extra and 1.4 tons per cubic yard.
- Area: 12 × 12 = 144 sq ft
- Volume: 144 × (4 ÷ 12) = 48 cu ft, which is 1.78 cu yd
- With 10 percent extra: 1.96 cu yd
- Weight: 1.96 × 1.4 = 2.74 tons
You would order about 2.7 tons, and a little more if your supplier advises for compaction.
Questions
How much does crushed stone weigh per cubic yard?
Figures in guides vary, from about 2,700 pounds up to 3,200 pounds per cubic yard, which is roughly 1.35 to 1.6 tons, depending on the rock, size and moisture. The calculator starts at 1.4 tons per cubic yard. Use your supplier's figure if they give one, because the spread is wide.
What is the difference between #57 stone and 3/4-inch minus?
#57 is clean, angular stone of about three-quarters of an inch with very few fine particles, so water drains through it. Three-quarters-inch minus includes the fine dust left over from crushing, which helps it pack down tightly. Which one you need depends on whether you want drainage or a firm, compacted base, so ask your supplier.
How much extra should I order for compaction?
A compacted base ends up thinner than the loose stone you spread, so order more than the finished volume. The extra allowance field is there for this. Use the higher end of the 5 to 10 percent range, or more for a base you will compact hard, and ask your supplier or installer for a figure.
Do I need a base layer for a driveway?
A driveway carries much heavier loads than a patio, so the stone layer is usually thicker, and often laid in layers. The right depth depends on the ground and the vehicles, so get local advice for a driveway.
Can I use crushed stone for a path?
Yes. A compacted layer of crushed stone makes a firm, drained path. For a walking path over stable soil a thinner layer is common, and a deeper one is used on soft or clay soil.