How to calculate how much mulch you need
Mulch is sold two ways — in bags by the cubic foot, and in bulk by the cubic yard — so the trick is figuring out your volume and converting to whichever you're buying. Multiply your bed's length by its width for the area, then multiply by the depth to get the volume. Because depth is usually in inches while length and width are in feet, this calculator converts the units for you and gives both bag counts and cubic yards.
How deep should mulch be?
Two to three inches is the sweet spot for most beds. Thinner than that lets weeds push through and the soil dry out; much thicker can hold too much moisture against stems and roots. Around trees, keep mulch a few inches away from the trunk rather than piling it up against the bark.
Bags or bulk?
Bags are convenient for small jobs and easy to carry, but they cost more per cubic foot. Once you need more than about five or six cubic yards, a bulk delivery is usually cheaper and far less hauling. Use the table below to sanity-check your bag count.
| Cubic yards | 2 cu ft bags |
|---|---|
| 1 yard | ~14 bags |
| 2 yards | ~27 bags |
| 3 yards | ~41 bags |
| 5 yards | ~68 bags |
Frequently asked questions
How many bags of mulch in a cubic yard?
A cubic yard is 27 cubic feet, so it takes about 13.5 of the standard 2-cubic-foot bags to make one yard. The calculator rounds bag counts up so you don't come up short.
Does mulch settle?
A little. Wood mulch compresses slightly over the first few weeks, so ordering at the calculated depth (rather than below it) accounts for that naturally.
How often do I replace mulch?
Most organic mulch breaks down over a year or two. A common approach is topping up an inch each spring rather than removing and replacing everything.
Mulch calculation example
A 20-by-10-foot bed covered 3 inches deep requires 50 cubic feet, or about 1.85 cubic yards of mulch. If bags contain 2 cubic feet each, that is 25 bags before adding a small allowance for settling and uneven ground.
Related garden calculators
Estimate the rest of the project with the plant calculator, grass seed calculator, or gravel calculator.