How to figure out how much mulch you need
Mulch is sold by volume: cubic feet in bags, cubic yards in bulk. To find your volume, multiply the area of the bed by how deep you want the mulch, making sure everything is in feet first.
Cubic feet = length (ft) × width (ft) × depth (in) ÷ 12
Cubic yards = cubic feet ÷ 27 · Bags = cubic feet ÷ bag size
Example: a 20 × 4 ft bed at 3 inches deep is 20 × 4 × 3 ÷ 12 = 20 cubic feet. That's 10 bags of the 2 cu ft size, or about 0.74 cubic yards in bulk.
Coverage per cubic yard
| Depth | One cubic yard covers | One 2 cu ft bag covers |
|---|---|---|
| 1 in | 324 sq ft | 24 sq ft |
| 2 in | 162 sq ft | 12 sq ft |
| 3 in | 108 sq ft | 8 sq ft |
| 4 in | 81 sq ft | 6 sq ft |
Getting the depth right
- New beds: 2–3 inches suppresses weeds and holds moisture without smothering roots.
- Refreshing old mulch: 1–2 inches on top of what's already there is usually plenty. Measure the existing layer before ordering.
- Around trees: spread it wide and flat, and keep it a few inches clear of the trunk. Piling mulch against bark invites rot and pests.
- Pathways: wood chips on paths can go 3–4 inches deep, since there's nothing underneath to smother.
Measuring awkward beds
Curved and L-shaped beds are easier than they look. Break the bed into simple rectangles and circles, measure each one, and add them up using the "I know the area" option. For a kidney-shaped bed, measure the longest length and the average width; that's close enough for ordering mulch.
Frequently asked questions
How many bags of mulch are in a yard?
One cubic yard is 27 cubic feet, so it equals 13.5 bags of the common 2 cubic foot size, or 9 bags of the 3 cubic foot size.
How deep should mulch be?
For most garden beds, 2 to 3 inches is enough to hold moisture and block weeds. Go thinner (1 to 2 inches) when topping up last year's mulch, and keep it a few inches away from tree trunks and plant stems.
How much area does a yard of mulch cover?
A cubic yard covers about 324 square feet at 1 inch deep, 162 square feet at 2 inches, and 108 square feet at 3 inches.
Is bulk mulch cheaper than bags?
Usually, once you need more than two or three cubic yards. Bulk is priced per yard and often costs well under the price of 13.5 bags, though delivery fees can narrow the gap on small orders. Enter both prices above to compare.
Can I use this for wood chips, bark or compost?
Yes. The calculator works out volume, so it works for any loose material sold by the bag or cubic yard, including wood chips, pine bark, compost and rubber mulch.