Mulch & Gravel Calculator
By Stephen Morrison, Editor Last reviewed
Enter your bed, path or tree ring and get cubic yards for a bulk order, bag counts and, for stone, tons. Works for mulch, pea gravel, crushed stone and river rock.
Quick answer: a 10 × 20 ft bed with 3 inches of mulch needs 50 cubic feet, which is 1.85 cubic yards. Order 2 yards in bulk or buy 25 bags of 2 cu ft mulch.
How the calculator works
Volume: area (sq ft) × depth (in) ÷ 12 = cubic feet
Yards: cubic feet ÷ 27
Bags: cubic feet ÷ bag size, rounded up
Tons: cubic yards × tons per yard (stone only)
Bulk orders are rounded up to the next half yard. Ask your supplier about their minimum order and delivery fee.
Coverage of one cubic yard
| Depth | One cubic yard covers |
|---|---|
| 1 in | 324 sq ft |
| 2 in | 162 sq ft |
| 3 in | 108 sq ft |
| 4 in | 81 sq ft |
Bags per cubic yard
| Bag size | Bags per cubic yard | Typical use |
|---|---|---|
| 0.5 cu ft | 54 | Decorative stone, pea gravel |
| 1.5 cu ft | 18 | Mulch, soil |
| 2 cu ft | 13.5 | Most bagged mulch |
| 3 cu ft | 9 | Mulch, soil |
How deep to spread it
- Mulch beds and tree rings: 2–3 inches once settled. Pull it back a few inches from trunks and stems, and never pile it into a "volcano".
- Flower beds: less is fine, especially around annuals.
- Gravel paths: 2–3 inches of pea gravel on a firm base. Edging keeps it in place.
- Topping up: measure what's left before you buy. Old mulch counts toward the depth.
Common questions
How much area does a yard of mulch cover?
At 3 inches deep, 108 sq ft. At 2 inches, 162 sq ft. The math: a cubic yard is 27 cubic feet, so coverage = 27 × 12 ÷ depth in inches.
How many bags of mulch make a yard?
13.5 bags of 2 cu ft mulch make one cubic yard, so buy 14. With 3 cu ft bags it's 9.
How deep should mulch be?
University of Illinois Extension recommends 2 to 3 inches once it settles, for landscape beds and rings around established trees. Keep it pulled back from trunks and stems: mulch piled against bark softens it and invites rot and insects.
How much does a yard of gravel weigh?
Roughly 1.3 to 1.5 tons, depending on the stone and how wet it is. We use 1.4 tons as a planning figure. If your supplier sells by the ton, ask for their weight per yard and enter it under "More options".
Is bulk or bagged cheaper?
For anything over about a yard, bulk delivery often costs less per yard, but delivery fees and minimums apply. Bags are easier for small beds and top-ups. Enter both prices under "More options" to compare.
How much gravel for a path?
A 30 ft × 3 ft path at 2 inches deep takes 0.56 cubic yards of pea gravel: about 0.78 tons, or 30 bags of 0.5 cu ft.
Sources
- University of Illinois Extension, "Mulch madness": 2–3 in once settled; avoid mulch volcanoes
- UF/IFAS Florida-Friendly Landscaping, Principle 4: mulch at a depth of 2–3 in
Formulas and figures last checked against these sources on. Spotted an error? Tell us and we'll fix it.
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