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How Much Mulch Do I Need?
Mulch is sold by the bag and by the bulk cubic yard. The right amount comes down to your bed area, the depth you want, and knowing when a bulk delivery beats hauling bags. Here's the quick math.
The formula
Multiply your bed area by the depth, keeping units straight. The quick version for cubic yards:
(324 is simply 27 cubic feet per yard × 12 inches per foot.)
Coverage at common depths
| Depth | 1 cubic yard covers |
|---|---|
| 2 in | ~162 sq ft |
| 3 in | ~108 sq ft |
| 4 in | ~81 sq ft |
For most beds, 2–3 inches is the sweet spot — enough to suppress weeds and hold moisture without smothering roots.
Bags or bulk?
Mulch bags come in 2 cu ft and 3 cu ft sizes. Since a cubic yard is 27 cubic feet:
- 2 cu ft bags: 27 ÷ 2 = 13.5 bags per yard
- 3 cu ft bags: 27 ÷ 3 = 9 bags per yard
Rule of thumb: under about 1 yard, bags are convenient. Above 2–3 yards, a bulk delivery is usually cheaper and far less hauling.
Worked example
A 300 sq ft bed at 3 inches deep:
- Cubic yards: (300 × 3) ÷ 324 = 2.8 cu yd
- In 2 cu ft bags: 2.8 × 13.5 = ~38 bags
At 38 bags, this is a clear case for ordering bulk.
Do it automatically
Frequently asked questions
How much mulch do I need?
(Area × depth in inches) ÷ 324 = cubic yards. At 2–3 in, a yard covers ~108–162 sq ft.
How many bags are in a yard of mulch?
13.5 bags of 2 cu ft, or 9 bags of 3 cu ft.
How deep should mulch be?
2–3 inches for most beds; avoid going past ~4 inches.