Mulch Calculator
Find how many cubic yards and bags of mulch your beds need
How to calculate how much mulch you need
Mulch is sold two ways: loose by the cubic yard for bulk delivery, and bagged in standard two-cubic-foot bags at the garden center. Both come from the same volume calculation, so the only real question is your bed area and how deep you want the mulch.
Multiply the bed's length by its width for the area in square feet, multiply by the depth in feet (inches ÷ 12) for cubic feet, then divide by 27 for cubic yards or by 2 for the number of bags. A 6.1 × 3.05 m bed at 8 cm deep is 18.6 m² × 0.08 m = 1.42 m³ — about 1.45 m³, or 25 bags.
How deep should mulch be?
- Refreshing an existing bed: about 5 cm on top of what is already there.
- A new bed or bare soil: about 8 cm for weed suppression and moisture.
- No deeper than roughly 10 cm for wood mulch — more suffocates roots and traps moisture.
Bags or bulk?
One cubic yard equals about 13.5 standard two-cubic-foot bags. For a bed or two, bags are convenient and easy to move. Once you are past roughly a cubic yard — about 14 bags — bulk delivery is usually cheaper per cubic foot, as long as you can spread it reasonably soon after it lands in the driveway.
Frequently asked questions
How many bags of mulch are in a cubic yard? A cubic yard is 27 cubic feet, and standard bagged mulch is 2 cubic feet per bag, so a cubic yard is 13.5 bags. Round up to 14 bags to fully cover a cubic yard of coverage.
How much does a cubic yard of mulch cover? At 8 cm deep, one cubic yard covers about 10 m². At 5 cm it stretches to about 15.1 m², and at 10 cm it covers only about 7.5 m².
When is the best time to mulch? Mid to late spring is common: the soil has warmed, weeds are just starting, and a fresh layer locks in moisture ahead of summer. A lighter fall top-up helps insulate roots over winter.
Should mulch touch plant stems or tree trunks? No. Pull mulch back a couple of inches from stems and trunks — piling it against the bark (a "mulch volcano") traps moisture and invites rot and pests. See our outdoor and garden guides for more.