Mulch and Gravel Calculator
Find how much mulch, gravel, pea gravel, sand or topsoil you need in cubic yards, bags and weight, for one bed or several areas added together.
How it works
Choose a material. Each one loads a typical density (pounds per cubic yard) and a waste or compaction allowance, both of which you can edit to match your supplier.
Add one or more areas as rectangles, circles or triangles. The calculator sums their square footage, multiplies by your depth in inches and divides by 12 to get cubic feet, then by 27 for cubic yards. In metric, square meters times depth in centimeters divided by 100 gives cubic meters.
You get the volume with your allowance, the weight in pounds and US tons (or kilograms and tonnes), bag counts rounded up, optional cost, and how many square feet one cubic yard covers at your depth.
Formula
ft³
Where:
- area
- = Sum of all rectangles, circles (π × (D ÷ 2)²) and triangles (base × height ÷ 2)
- depth
- = Layer thickness in inches or centimeters
- density
- = Pounds per cubic yard, for example 600 for mulch and 2,800 for gravel
- 324
- = Square feet one cubic yard covers at 1 inch deep (27 × 12)
Worked example
A 20 ft by 10 ft flower bed is 200 square feet. At 3 inches deep that is 200 × 3 ÷ 12 = 50 cubic feet, or 50 ÷ 27 = 1.8519 cubic yards, which is 25 bags of 2 cubic feet.
If the same area were gravel at 2,800 lb per cubic yard, it would weigh 1.8519 × 2,800 = 5,185.2 lb, about 2.593 US tons. At 3 inches, each cubic yard covers 108 square feet.
Tips for Ordering Landscape Material
Bulk landscape yards sell by the cubic yard, while garden centers sell bags by the cubic foot. Compare both: once a project needs more than about two cubic yards, bulk delivery is usually cheaper even after the delivery charge. Ask whether the price is for loose or compacted material, since gravel settles after it is spread.
Weight matters for hauling. A cubic yard of gravel weighs around 1.4 tons, which is more than most half-ton pickups should carry in one trip. Mulch is much lighter, so a single truck bed can hold far more of it by volume. Check your vehicle's payload rating before loading material yourself.
Getting the Depth Right
Mulch works best at 2 to 3 inches. Thinner layers let weeds through, while deeper layers can starve roots of air and hold too much moisture against stems and trunks. Keep mulch a few inches away from tree bark and house siding to discourage rot and pests.
For gravel paths, lay landscape fabric and 2 to 4 inches of stone. Driveways need a compacted base and 4 to 6 inches of gravel on top. Sand under pavers is typically about an inch, and new lawns do well with 4 to 6 inches of quality topsoil. Edit the waste field if your supplier recommends a different compaction allowance.
Frequently asked questions
One cubic yard covers 324 square feet at 1 inch deep, 162 at 2 inches and 108 at 3 inches. Divide 324 by your depth in inches for any other thickness.