Gravel Calculator
Enter the length, width and depth of your area and this gravel calculator returns the volume in cubic yards, the weight in tons, and the coverage, so you can order crushed stone by either unit. It works for driveways, paths, drainage beds and the compacted base under a concrete slab.
Gravel Calculator
Quarries sell gravel by the ton, but it is easier to plan by volume, so this tool gives you both. The link between them is density, which for crushed stone runs around 1.4 tons per cubic yard.
How to calculate gravel
Volume equals length times width times depth, all in the same unit, divided by 27 for cubic yards. To get tons, multiply the cubic yards by the density in tons per cubic yard.
How deep should gravel be
Depth depends on the use. A base under a concrete slab needs 4 to 6 inches of compacted crushed stone, placed in 2 inch lifts and compacted between each. A gravel driveway usually runs 4 to 8 inches total, often in two layers with larger stone below and finer stone on top. A simple garden path can work at 2 to 3 inches.
| Use | Depth | Cubic yards per 100 sq ft |
|---|---|---|
| Garden path | 2 to 3 in | 0.62 to 0.93 |
| Slab base | 4 to 6 in | 1.23 to 1.85 |
| Driveway | 4 to 8 in | 1.23 to 2.47 |
Worked example, a slab base
You are placing a 4 inch stone base under a 12 by 12 foot slab. The footprint is 144 square feet. Convert the depth: 4 divided by 12 is 0.333 feet. Multiply: 144 times 0.333 is 48 cubic feet, which is 1.78 cubic yards. At 1.4 tons per cubic yard, that is about 2.5 tons. Order a little extra, since compaction and an uneven subgrade both use more than the flat calculation shows.
Coverage at a glance
One cubic yard of gravel covers about 100 square feet at 3 inches deep, 160 square feet at 2 inches, or 80 square feet at 4 inches. Use these as a quick check against the calculator before you order.
Related calculators
- Tons to cubic yards calculator to convert a quarry quote
- Concrete slab calculator for the slab above the base
- How to calculate concrete guide for volume formulas
Frequently asked questions
How much gravel do I need?
Multiply length by width by depth, divide by 27 for cubic yards, then multiply by about 1.4 to get tons. A 4 inch base under a 12 by 12 slab needs about 1.78 cubic yards, or 2.5 tons.
How many tons are in a cubic yard of gravel?
About 1.3 to 1.5 tons, depending on stone size and moisture. A common planning figure is 1.4.
How deep should gravel be under a concrete slab?
Use 4 to 6 inches of compacted crushed stone, placed in 2 inch lifts, with each lift compacted before the next.
What kind of gravel goes under concrete?
Angular crushed stone compacts and locks together, so it makes a stable base. Round pea gravel shifts under load and is a poor base choice.
How much does a yard of gravel cover?
About 100 square feet at 3 inches deep, or 80 square feet at 4 inches.
References
- Inch Calculator, gravel weight and coverage references: https://www.inchcalculator.com/gravel-calculator
- Portland Cement Association, subgrade and base guidance: https://cement.org
- United States Geological Survey, construction aggregate data: https://www.usgs.gov
Methodology: volume uses length times width times depth divided by 27, with tons from a typical crushed stone density of about 1.4 tons per cubic yard. Density and compaction vary, so a supplier figure is most accurate. Estimates are for planning. Recommended: attribute this page to a named author and add a review date.