Landscape rock calculator: how much rock you need
Pick the rock, enter the area and depth, and get cubic yards, tons and bag count. The weight per yard for each rock is shown and editable, so you can match your supplier.
Typical value for this rock. Change it if your supplier quotes a different weight.
Depth
Suggested for this rock: 3 in.
200 sq ft of river rock at 3 in deep
1.85 cubic yards
2.5 tons (5,000 lb) · 50 cu ft
Bulk order
Order 2.5 tons. Yards sell stone by the ton or half ton and usually charge a delivery fee.
Bagged
100 bags of 0.5 cu ft
About 50 lb per bag at this weight.
Rule of thumb
One ton covers about 80 sq ft at 3 in deep.
Assumes 2,700 lb per cubic yard for river rock. Real weight varies with stone size, source and moisture, so check your supplier's number.
How the landscape rock calculator works
Rock is a volume problem first and a weight problem second. Multiply the area in square feet by the depth in inches and divide by 12 to get cubic feet. Divide by 27 for cubic yards. Then multiply cubic yards by the weight of one cubic yard of that rock, and divide by 2,000 for tons. Landscape yards quote stone by the ton, and bags are sold by volume (usually 0.5 cubic feet), so you need both numbers.
The weight is where most calculators quietly differ. A cubic yard of stone is not a fixed weight: it depends on the rock, the size of the pieces and how wet the pile is. The calculator uses standard approximate values and shows them so you can change them. If your supplier says their river rock is 2,900 pounds a yard, type that in.
| Rock | Assumed lb per cu yd | Tons per cu yd | Usual depth |
|---|---|---|---|
| Pea gravel (3/8 in) | 2,800 | 1.4 | 2 to 3 in |
| River rock (1 to 3 in) | 2,700 | 1.35 | 2 to 3 in |
| Crushed stone (3/4 in) | 2,700 | 1.35 | 3 to 4 in |
| Lava rock | 1,000 | 0.5 | 2 to 3 in |
| Decomposed granite | 3,000 | 1.5 | 3 in, compacted |
| Marble chips / white rock | 2,700 | 1.35 | 2 in |
Worked example
A side-yard bed 20 feet long and 10 feet wide, covered with river rock 3 inches deep. Area: 200 square feet. Volume: 200 × 3 ÷ 12 = 50 cubic feet, and 50 ÷ 27 = 1.85 cubic yards. Weight: 1.85 × 2,700 = 5,000 pounds, which is 2.5 tons.
Bagged, that is 100 bags of 0.5 cubic feet, each about 50 pounds. Bulk, you would order 2.5 tons. The same bed in lava rock is still 1.85 cubic yards, but only about 0.93 tons, because lava rock is full of air pockets. That is why lava rock is often sold by the yard rather than the ton: ask which unit the price is in.
How deep to spread landscape rock
Small rock covers well at 2 inches; larger rock needs more depth to hide the soil or fabric between stones. A good rule is a depth about twice the size of the stone, and no less than 2 inches. Pea gravel paths are usually 2 to 3 inches over a compacted base: deeper than that and it feels like walking on a beach. Decomposed granite is laid about 3 inches and compacted. River rock of 1 to 3 inches needs 2 to 3 inches, and large 3 to 5 inch cobbles more.
- Lay landscape fabric under decorative rock, or it sinks into the soil and weeds come through.
- Add an edging (steel, stone or plastic) so the rock stays out of the lawn.
- For a path or patio base, compact a layer of crushed stone first and put the decorative rock on top.
Bags or bulk
A 0.5 cubic foot bag of river rock or pea gravel weighs around 50 pounds. Fifty-four bags make one cubic yard. Bags make sense for a small bed or a top-up; for anything over about a cubic yard, bulk from a landscape supply yard is usually cheaper per ton even after the delivery fee, and saves you lifting a few tons of rock one bag at a time. If you enter your supplier's price per ton, the calculator shows the bulk cost.
See it on your yard
Upload a photo and preview a rock garden, gravel path or xeriscape on your actual yard before ordering a single ton. 3 free designs, no credit card.
Redesign my yard freeFrequently asked questions
How many tons of rock do I need?⌄
Square feet × depth in inches ÷ 12 ÷ 27 gives cubic yards. Multiply by the rock's weight per cubic yard (about 2,700 lb for river rock or crushed stone) and divide by 2,000. A 200 square foot bed at 3 inches of river rock needs about 2.5 tons.
How much does a cubic yard of landscape rock weigh?⌄
Approximately 2,700 to 3,000 pounds for most gravel, river rock, crushed stone and decomposed granite, and around 1,000 pounds for lava rock. It varies with stone size and moisture, so use your supplier's figure when you have it.
How much area does a ton of river rock cover?⌄
At 2 inches deep, about 120 square feet. At 3 inches, about 80. These assume 2,700 pounds per cubic yard.
How many bags of rock are in a cubic yard?⌄
A cubic yard is 27 cubic feet, so 54 bags of 0.5 cubic feet, 36 bags of 0.75 cubic feet, or 27 bags of 1 cubic foot.
Is landscape rock the same as gravel?⌄
Gravel is one kind of landscape rock. The math is identical; only the weight per yard changes. Pick the closest type in the calculator or type in your own weight.