How much mulch does your bed need? Get cubic yards, cubic feet and the number of bags for any bed size and depth.
| Input | Result |
|---|---|
| 20 × 10 ft, 3 in deep (2 ft³ bags) | 1.85 yd³ · 25 bags |
| 30 × 5 ft, 2 in deep (2 ft³ bags) | 0.93 yd³ · 13 bags |
| 12 × 12 ft, 4 in deep (3 ft³ bags) | 1.78 yd³ · 16 bags |
The volume you need is the same either way; only the unit differs. Bulk mulch is sold by the cubic yard and bagged mulch by the cubic foot, and one cubic yard is 27 cubic feet, so a yard is 13.5 of the common 2 ft³ bags. Past roughly a yard, bulk is normally the cheaper route; below that, bags win on convenience and on not having a pile sitting on the driveway.
Depth is the number people get wrong. Two to three inches is the usual bed recommendation. Less than two and weeds push through; more than about four and the layer starts to shed water instead of letting it through, and holds moisture against stems. Keep it pulled back from the base of shrubs and trees rather than mounded against them.
Bagged volume is nominal and settles, so the count is an estimate of what to buy, not a measure of what will be in the bag when you open it. If the bag prints a cubic-foot figure, use it.
Two to three inches is the usual recommendation for beds. Shallower than two inches lets weeds through, and deeper than about four inches can shed water and keep too much moisture against stems and trunks. Keep mulch pulled back from the base of plants.
13.5, because a cubic yard is 27 ft³. The calculator rounds up to whole bags, since that is how mulch is sold.
Bagged mulch is sold by volume but settles and compacts, and nominal bag volumes vary between products. Check the cubic-foot figure printed on the bag and enter it in the bag size field.
Usually, once you pass roughly a cubic yard, bulk mulch is sold by the yard and avoids the cost of bagging. Bags stay practical for small beds or where a truck cannot reach.