How much does a yard of mulch cover?
| Depth | 1 cubic yard covers | Cubic yards per 100 sq ft | 2 cu ft bags per 100 sq ft |
|---|---|---|---|
| 1 inch | 324 sq ft | 0.31 | 5 |
| 2 inches | 162 sq ft | 0.62 | 9 |
| 3 inches | 108 sq ft | 0.93 | 13 |
| 4 inches | 81 sq ft | 1.23 | 17 |
| 6 inches | 54 sq ft | 1.85 | 25 |
So at the usual 3 inches, a cubic yard covers about 108 square feet, roughly a 4 × 27 ft bed. A 2 cubic foot bag covers 8 square feet at 3 inches.
How deep should mulch be?
The University of Illinois Extension recommends a layer of 2 to 4 inches on well-drained sites: 2 to 3 inches for composted material and 3 to 4 inches for coarse mulch like wood chips or shredded bark. More is not better: thick layers mat down and keep water and air from reaching roots, and mulch piled against a tree trunk ("volcano mulching") is one of the most common causes of tree decline.
- Keep mulch at least 4 inches away from tree trunks, and away from the stems of shrubs.
- Around a tree, spread it out toward the dripline. Illinois Extension says a ring with a 3-foot radius (a 6-foot circle) is the maximum most trees need.
- If there's already mulch, measure it before buying more. Often you only need to top it up to the 2–4 inch range, or just rake the old layer to freshen it.
How the calculator works
Volume is area × depth, with the depth converted from inches to feet. A 20 × 4 ft bed is 80 square feet; at 3 inches deep that's 80 × 3 ÷ 12 = 20 cubic feet. Divide by 27 for cubic yards (0.74), or by the bag size for bags (10 bags of 2 cubic feet). Bags are rounded up. For a circle, the area is π × radius², so a 6-foot tree ring is about 28 square feet.
Bags or bulk?
One cubic yard equals 13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet. Bagged mulch is easy to carry and store; bulk is usually cheaper per yard for big jobs but often comes with a delivery charge, so compare the total price for your amount.
FAQ
How many bags of mulch are in a yard?
13.5 bags of 2 cubic feet, 9 bags of 3 cubic feet, or 18 bags of 1.5 cubic feet. A cubic yard is 27 cubic feet.
How many bags of mulch do I need for 100 square feet?
At 3 inches deep, 100 square feet takes 25 cubic feet: 13 bags of 2 cubic feet (12.5, rounded up), or 0.93 cubic yards bulk.
Does this work for soil, compost, or gravel?
Yes. It's the same volume math for anything sold by the cubic foot or cubic yard. Use the depth you need: raised beds and new lawns are usually deeper than mulch, so the topsoil calculator adds an allowance for settling. For gravel sold by the ton, use the gravel calculator.
Does mulch settle?
Fluffy mulches like shredded bark settle a bit after watering and break down over the season, which is why most beds need a top-up each year or two. If you want a full 3 inches after settling, add a little extra.
Source for depth and trunk spacing: University of Illinois Extension, Proper Mulching Techniques.