How much mulch do I need?
Multiply the bed's area in square feet by the depth in feet to get cubic feet, then divide by 27 for cubic yards. The calculator does it for rectangles, circles (tree rings) and triangles, and you can add several identical beds at once.
Example: a 20 × 10 ft bed at 3 inches deep is 200 × 0.25 = 50 cu ft, which is 1.85 cubic yards, or 25 bags of 2 cu ft.
Recommended mulch depth
| Where | Depth |
|---|---|
| Fine or composted mulch | 2–3 in |
| Bark nuggets, wood chips | 3–4 in |
| Around annual flowers | 1–2 in |
| Topping up an existing bed | 1–2 in |
More is not better. Layers deeper than about 4 inches can mat and keep water and oxygen from reaching roots, which is why every extension guide puts an upper limit on depth.
Coverage of one cubic yard
| Depth | Covers | 2 cu ft bags per 100 sq ft |
|---|---|---|
| 1 in | 324 sq ft | 5 |
| 2 in | 162 sq ft | 9 |
| 3 in | 108 sq ft | 13 |
| 4 in | 81 sq ft | 17 |
Tips
- Pull weeds and water the soil before you spread mulch.
- Keep mulch a few inches away from tree trunks and house siding.
- Rake old mulch to loosen it before topping up, so you only add what's needed.
