Key takeaways
- Mulch volume = bed area × depth, with depth converted from inches to feet.
- Mulch is sold in cubic yards or in 2-cubic-foot bags; about 13.5 bags fill one cubic yard.
- One cubic yard covers 108 sq ft at 3 inches deep (or 162 sq ft at 2 inches).
- Aim for a 2–3 inch layer and refresh it annually rather than piling on more.
How to estimate mulch
Mulch is sold in cubic yards or in 2-cubic-foot bags; about 13.5 bags fill one cubic yard. Bagged mulch suits small beds, while bulk by the cubic yard is cheaper for larger jobs. To size an order, find the bed's volume in cubic feet, then convert to cubic yards for bulk or to bags for a small bed.
Depth is entered in inches because mulch is spread that way, so it's divided by 12 to convert to feet before multiplying by the bed area.
Worked example: a 20 × 8 bed at 3 inches
For a 20 ft × 8 ft bed (160 square feet) spread 3 inches deep: 160 × (3 ÷ 12) = 40 cubic feet, which is 40 ÷ 27 = 1.48 cubic yards. In bags that's 40 ÷ 2 = 20 of the 2-cubic-foot bags, or 14 of the 3-cubic-foot bags. At 20 bags, ordering bulk by the yard is the easier and cheaper call.
Coverage by depth
How far one cubic yard of mulch goes depends entirely on how thick you spread it:
| Depth | Coverage per cubic yard |
|---|---|
| 1 inch | 324 sq ft |
| 2 inches | 162 sq ft |
| 3 inches | 108 sq ft |
| 4 inches | 81 sq ft |
Bags or bulk?
For small beds, bagged mulch is convenient and skips delivery fees. Past about 6–8 bags, bulk mulch by the cubic yard is usually cheaper and far less hauling. Whichever you choose, refresh to a 2–3 inch depth each year rather than burying the crowns of your plants. For a stone mulch or decorative rock instead, size it with the gravel calculator.
Frequently asked questions
How much mulch do I need?
Bed area × depth (in) ÷ 12 gives cubic feet; divide by 27 for cubic yards. A 20×8 bed at 3″ ≈ 1.48 cubic yards.
How many bags in a cubic yard?
About 13.5 of the 2-cubic-foot bags, or about 9 of the 3-cubic-foot bags, fill one cubic yard.
How many bags for 200 square feet?
At 2″ deep, 200 sq ft needs ≈ 33.3 cubic feet — about 17 of the 2-cubic-foot bags. At 3″ it's 50 cubic feet, or 25 bags.
How deep should mulch be?
2–3 inches for most beds — enough to block weeds and hold moisture without smothering roots.
How much area does a yard cover?
About 324 sq ft at 1″, 162 sq ft at 2″, 108 sq ft at 3″, and 81 sq ft at 4″ deep.
Bagged or bulk — which is cheaper?
Bagged for small beds; past ~6–8 bags, bulk by the cubic yard is cheaper and far less hauling.
Coverage figures follow standard landscape guidance — one cubic yard covers about 324 sq ft at 1 inch deep, per university extension guidance. The 27 cubic feet per cubic yard conversion is exact.
Last reviewed June 2026