Gravel Calculator
Use this gravel calculator to work out how much a driveway, path or bed needs, in cubic yards and in tons for ordering by weight.
Rectangular Area
Circular Area
Fire pits, tree rings and round patios.
Gravel Driveway
A driveway is built in layers, not one pour of decorative stone, this works out the base and the top course separately.
Coverage From Tonnage
The other direction: you know how many tons you can get, and want to know how far it goes.
Aquarium Gravel
Measure the inside of the tank. Aquarium gravel is sold by weight, so the answer is in pounds.
Gravel Cost
How to use the Gravel Calculator
Start with the depth, because it moves the order more than the area does. Two to three inches suits a path or a decorative bed; a driveway wants four inches or more, usually over a compacted base. Picking the material changes the weight, not the volume, order by the cubic yard where you can, because that figure is exact.
There are six tabs, because a driveway and a fish tank are not the same problem:
- Rectangular Area and Circular Area, the everyday cases. A circular bed takes a diameter, not a radius.
- Gravel Driveway, two layers rather than one. Enter the base depth and the top depth separately and set a compaction allowance, because a driveway gets rolled and loose stone loses depth as it beds in.
- Coverage From Tonnage, the calculation run backwards. You know three tons is what fits on the truck; this tells you how far it goes at a given depth.
- Aquarium Gravel, inches of substrate rather than yards of stone, answered in bags.
- Gravel Cost, prices the same area by the yard or by the ton, whichever way your supplier quotes, with delivery on top.
Gravel formula
Volume is straightforward geometry:
- Rectangle:
length × width × depth - Circle:
π × (diameter ÷ 2)² × depth cubic yards = cubic feet ÷ 27
Tonnage applies a density:
tons = cubic yards × lb per cubic yard ÷ 2,000
| Material | Approx. lb per cubic yard | Tons per yard |
|---|---|---|
| Pea gravel | 2,800 | 1.40 |
| Crushed stone (#57) | 2,835 | 1.42 |
| Base rock / road base | 2,900 | 1.45 |
| River rock | 2,700 | 1.35 |
| Decomposed granite | 2,750 | 1.38 |
| Sand | 2,700 | 1.35 |
Worked example
A 40 ft × 12 ft driveway at 3 inches of crushed stone, 5% waste:
- Area: 40 × 12 = 480 sq ft
- Depth: 3 in = 0.25 ft. Volume: 480 × 0.25 = 120 ft³
- Cubic yards: 120 ÷ 27 = 4.44, plus 5% = 4.67 yd³
- Weight: 4.67 × 2,835 = 13,241 lb = 6.6 tons
What the result means
The cubic yard figure is exact. The tonnage is an estimate. Loose material density shifts with moisture, how tightly it is packed and where it was quarried, published charts for the same material can differ by a wide margin, and wet gravel can run 15 to 20 percent heavier than dry.
Order by the yard when the supplier offers it. If they sell by weight, treat the tons figure as a starting point and confirm their own conversion for that material.
Common mistakes
- Ordering by tons off a generic density. Ask the yard what a cubic yard of that specific material weighs. It is the one number that varies most.
- Going too shallow on a driveway. Three inches of loose stone over soft ground rutts quickly. Driveways usually want a compacted base course underneath the decorative layer.
- Forgetting compaction. Base rock settles noticeably once rolled, so the finished depth is less than the loose depth you ordered.
- Measuring the top of a slope. Sloped or dished areas hold more than their footprint suggests.
Frequently asked questions
How many tons of gravel are in a cubic yard?
Between about 1.35 and 1.45 tons for most gravels, so a rough rule of 1.4 tons per cubic yard works for estimating. Wet material runs heavier. Confirm the figure with your supplier before ordering by weight.
How deep should gravel be?
Two to three inches for a garden path or decorative bed. Four inches or more for a driveway, usually over a separate compacted base layer. Deeper layers are laid and compacted in stages rather than all at once.
How much gravel do I need for a 40×12 driveway?
At 3 inches deep that is 4.44 cubic yards, or about 4.7 yards with a 5 percent allowance, roughly 6.6 tons of crushed stone. At 4 inches it rises to about 5.9 yards.
Should I order gravel by the ton or by the yard?
By the yard if you have the choice, because volume is what you actually need and the conversion to weight is the uncertain step. Many suppliers only sell by weight, in which case ask them for their own tons-per-yard figure for that material.
Does gravel settle after it is laid?
Angular crushed stone locks together and settles a little. Base rock settles a lot once compacted, which is the point of it. Rounded materials like pea gravel and river rock stay loose and shift underfoot, which is why they suit beds better than driveways.
Sources and assumptions
Volume is exact geometry. Densities are mid-range values drawn from landscape supplier charts, which put sand, gravel and rock at roughly 2,500 to 2,900 lb per cubic yard.
Published figures for the same material disagree, sometimes substantially, because moisture, compaction and mineral source all move the weight. That is why this calculator leads with cubic yards and treats tonnage as a secondary estimate.
Confirm quantities and the supplier’s own weight conversion before ordering.