How deep?
Two to three inches in a planted bed, three to four where weeds are the problem. Topping up an established bed usually means one inch, not a full layer.
Mulch calculator
Beds and tree rings — in cubic yards, bags and cost.
Frequently asked questions
How many bags of mulch in a cubic yard?
13.5 two-cubic-foot bags, 18 of the 1.5-cubic-foot bags, or 9 of the 3-cubic-foot bags.
How much does a yard of mulch cover?
108 square feet at 3 inches deep, 162 at 2 inches, 81 at 4 inches.
How much mulch for a 20 × 5 ft bed?
That is 100 square feet. At 3 inches you need 25 cubic feet — 0.93 cubic yards, or 13 bags.
How often should mulch be replaced?
Bark breaks down over a season, so most beds get an inch topped up once a year rather than a full replacement.
Bags or bulk?
A cubic yard is 13.5 of the 2-cubic-foot bags. Past about two yards, bulk delivery normally wins on price and saves a lot of lifting.
What this calculator assumes
- A cubic yard is 27 cubic feet: 108 sq ft at 3 in, 162 at 2 in, 81 at 4 in.
- Bag volumes are as labelled — 2 ft³ is the common size.
- Weight assumes dry bark at about 600 lb per cubic yard; rain can double it.