Use this free gravel calculator to find how many cubic yards and tons of gravel, pea gravel, crushed stone, river rock, road base or sand you need for a driveway, path, garden bed, trench or patio base. Enter a rectangle, circle or triangle, the depth and an extra for settling, and you get the amount to order in cubic yards and tons, with the cost if you add a price. Choose your material and its usual density is filled in, or type your supplier's figure. Switch to Tons to Yards to change tons, tonnes or pounds into cubic yards, or to What It Covers to find the area a load will cover at a depth. Every answer shows the working, and tables list the weight of each material, what gravel covers and gravel sizes. It is free and instant, and your numbers stay in your browser.
How to calculate how much gravel you need
Gravel is sold by volume, in cubic yards, and often by weight, in tons. Work out the volume of the area you want to cover, add a little extra for settling, then use the weight of the stone to find the tons. For a rectangle the volume is length × width × depth. Measure the length and width in feet and the depth in inches, turn the inches into feet by dividing by 12, and divide the cubic feet by 27 to get cubic yards.
40 × 12 × (4 ÷ 12) = 160 cubic feet160 ÷ 27 = 5.93 cubic yardsWith 10% extra for settling you would order about 6.52 cubic yards, which is about 9.24 tons of gravel.
Cubic yards and tons
Suppliers sell gravel by the ton or by the cubic yard, so you need both. A cubic yard of loose, dry gravel or crushed stone weighs about 1.4 tons (2,800 pounds), which is 105 pounds per cubic foot. Pea gravel and sand are a little lighter, at about 1.35 tons per cubic yard, and road base and decomposed granite are heavier. The weight depends on the stone, its size and how wet it is, so use your supplier's figure when you have it. The Tons to Yards tab changes between tons, tonnes, pounds, cubic yards, cubic feet and cubic meters.
How deep should the gravel be?
Walkways, patios and decorative beds are often 2 to 3 inches deep. Driveways are often 4 to 6 inches, laid on a firm base. Drainage trenches can be 6 to 12 inches or more. The right depth depends on the stone, the ground and the traffic, so check with a landscaper or your supplier.
Gravel for a driveway
For a driveway, measure the length and the average width, choose the depth, and add 10% for settling. A driveway 40 ft by 12 ft at 4 inches deep needs 6.52 cubic yards with that extra. For a curved or odd shape, split it into rectangles, circles and triangles, work out each one, and add them up. The calculator has all three shapes.
Pea gravel, crushed stone, river rock and road base
The maths is the same for every stone. Only the weight changes. Choose the material in the calculator and its usual density is filled in, or type your supplier's density to use it instead. Road base and crusher run are packed with fine stone, so they weigh more per cubic yard than clean, rounded pea gravel.
What one ton covers
One cubic yard covers 27 square feet at a depth of 1 foot, so it covers 108 square feet at 3 inches and 81 square feet at 4 inches. One ton of gravel is about 0.7 cubic yards, so it covers about 76 square feet at 3 inches. The What It Covers tab works out the area from the amount you have and the depth.
Extra for settling and waste
Loose gravel settles when it is walked on or compacted, and some is lost at the edges. Most people add 5 to 10%. If you are laying it over soft ground you may need more, and it is better to have a little left over than to order a second small load.
Tons and tonnes
A US ton is 2,000 pounds, or about 907 kilograms. A metric tonne is 1,000 kilograms, or about 2,205 pounds. Switch the units to meters and centimeters and the answer is in cubic meters and tonnes.
Calculators that go with this one
To pour a slab, footing or post holes, use the Concrete Calculator. To work out the extra for settling, see the Percentage Calculator, and to turn inches into a fraction of a foot, the Fraction Calculator.
