Free tool
Landscape Rock Calculator
Measure the beds or the feature, pick a depth, and this works out the cubic yards. Decorative rock is sold by the cubic yard, so this is the number you order with.
Getting the depth right
- Larger stone needs a deeper layer to cover the ground. A 2½ inch rock at 2 inches deep is a single layer with gaps in it.
- Put a ground-cover fabric down first. Rock without it works its way into the soil and you are buying it twice.
- Rock beds are not walking routes. If people will cross it regularly, a compacted pathway material is the better choice.
The maths behind it
Length times width gives square feet. Multiply that by the depth in inches, then divide by 324. The answer is cubic yards. One cubic yard covers 324 square feet at 1 inch deep, or 100 square feet at about 3¼ inches deep.
The 324 comes from a cubic yard being 27 cubic feet, and 27 times 12 inches is 324. Nothing else is going on, which is why you can check this calculator against a tape measure and a phone.
Materials this suits
Common questions
How much landscape rock do I need?
Multiply the length by the width in feet, multiply that by the depth in inches, then divide by 324. A 300 square foot bed at 3 inches deep needs about 2.8 cubic yards.
How deep should decorative rock be?
Three inches for rock up to about 1 inch across. Larger stone needs 4 inches or more, because the layer has to be at least a couple of stones thick to hide the ground.
How much does a yard of rock cover?
One cubic yard covers about 100 square feet at 3 inches deep. Larger river rock covers less, because it is laid deeper.
Should I put fabric under landscape rock?
Yes. A ground-cover fabric keeps the rock out of the soil and stops most weeds coming up through it. It is the cheapest part of the job and the one people skip.