Gravel Calculator
Find how many cubic yards and tons of gravel your project needs
How to calculate how much gravel you need
Gravel is priced two different ways — by the cubic yard when it is delivered loose, and by the ton when it is weighed at the quarry — so the first job of any estimate is to work out both. The volume is simple geometry; the weight depends on which stone you buy, because a cubic yard of dense crushed stone weighs noticeably more than the same volume of light pea gravel.
Start with the area you are covering in square feet, multiply by the depth in feet (depth in inches ÷ 12), and you have the volume in cubic feet. Divide by 27 to get cubic yards. A 20 × 10 ft path at 2 inches deep covers 200 sq ft, which at that depth is about 33 cu ft — roughly 1.2 cubic yards.
How deep should the gravel be?
- Paths and walkways: about 2 inches over a firm, level base.
- Driveways and heavy-use areas: about 4 inches, often over a coarser base layer.
- Drainage or a French drain: fill to the design depth of the trench, not a fixed rule.
Why the material changes the tonnage
The tonnage in your result uses a representative dry density for each stone: pea gravel is lighter, crushed stone and decomposed granite are heavier. Real weight shifts with stone size, how wet the pile is, and how much it has compacted, so treat the tonnage as a close estimate and confirm with your supplier before a large order.
Frequently asked questions
How many square feet does a ton of gravel cover? At a typical depth of 2 inches, one ton of average gravel covers roughly 100 square feet. Go deeper and it covers less: at 4 inches the same ton covers about 50 square feet. Use the calculator above for your exact depth rather than a single rule of thumb.
How much extra should I order? Add about 10 percent to the calculated volume. Gravel compacts under foot and vehicle traffic and settles into the ground beneath it, so ordering the bare volume usually leaves you short.
Should I buy bags or bulk? Bags suit small jobs of under about a cubic yard; beyond that, bulk delivery by the ton is almost always cheaper per unit, since one cubic yard is roughly 54 half-cubic-foot bags.
Do I need a base layer under the gravel? For driveways and areas that carry weight, yes — a compacted coarse base under the finish gravel spreads the load and stops the top layer from sinking into soft ground. See our outdoor and garden guides for details.