Mulch Calculator
Find how many cubic yards or bags of mulch you need to cover your garden beds. Enter your measurements for an instant result.
Tip: 2 to 3 inches of mulch is ideal for most beds. Too deep can suffocate roots. Bagged mulch is most often sold in 2 cubic foot bags, and bulk mulch is sold by the cubic yard (27 cubic feet).
How to calculate mulch
Mulch is sold by the cubic yard in bulk, or in bags of 1.5 to 3 cubic feet. You measure the bed area and desired depth, then convert to volume. The formula is:
Cubic yards = Length (ft) × Width (ft) × Depth (ft) ÷ 27
Depth is usually in inches, so divide by 12 to get feet. The calculator above gives both cubic yards and the number of bags for the size you choose.
Worked example
A bed 20 ft long and 10 ft wide, mulched 3 inches deep:
| Area | 20 × 10 = 200 ft² |
|---|---|
| Depth | 3 in ÷ 12 = 0.25 ft |
| Volume | 200 × 0.25 = 50 ft³ |
| Cubic yards | 50 ÷ 27 = 1.85 yd³ |
| Bags (2 cu ft) | 50 ÷ 2 = 25 bags |
Coverage by depth (per cubic yard)
| Depth | Area covered by 1 yd³ |
|---|---|
| 1 in | about 324 ft² |
| 2 in | about 162 ft² |
| 3 in | about 108 ft² |
Frequently asked questions
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it equals about 13.5 two-cubic-foot bags, or 18 bags at 1.5 cubic feet each.
How deep should mulch be?
Two to three inches is ideal for most garden beds. That is deep enough to suppress weeds and hold moisture without smothering plant roots.
How much mulch do I need for a 20x10 bed?
A 20 by 10 foot bed at 3 inches deep needs about 1.85 cubic yards, or roughly 25 two-cubic-foot bags. Use the calculator above for other depths.
Is bulk or bagged mulch cheaper?
For larger beds, bulk mulch by the cubic yard is usually cheaper per unit. Bags are more convenient for small areas or when you cannot take a bulk delivery.