How Much Mulch Do I Need? (Depth, Coverage & Bags)
Part of Landscaping & Aggregate
Quick answer
Multiply bed length × width to get square feet, choose a depth (2–3 inches is standard), then divide. At 3 inches, one cubic yard covers about 108 ft² and equals 13.5 of the standard 2 ft³ bags. The mulch calculator does the math from your measurements.
Buying mulch comes down to three numbers: the area of your beds, how deep you spread it, and whether you're buying bags or bulk. Get the first two right and the rest is simple division.
Step 1 — Measure the area
Measure each bed's length and width in feet and multiply for square footage. Add up all the beds. For curved or odd shapes, break them into rectangles and circles and total the pieces.
Step 2 — Pick a depth
Depth is what most people get wrong. Two to three inches suppresses weeds and holds moisture without smothering roots. Go deeper only on paths, and keep mulch off trunks and stems.
| Where | Depth |
|---|---|
| Annual flower beds | 1–2 in |
| Perennial & shrub beds | 2–3 in |
| Around trees (off the trunk) | 3 in |
| Pathways | 3–4 in |
Step 3 — Convert to bags or bulk
Volume in cubic feet = area × (depth in inches ÷ 12). Bagged mulch comes in 2 ft³ bags, so divide cubic feet by 2. Bulk mulch is sold by the cubic yard (27 ft³) and is cheaper once you need more than about 6–8 bags.
| Depth | Coverage per yd³ | 2 ft³ bags per yd³ |
|---|---|---|
| 2 in | 162 ft² | 13.5 bags |
| 3 in | 108 ft² | 13.5 bags |
| 4 in | 81 ft² | 13.5 bags |
Bags per yard doesn't change with depth — only the area you cover does. For the exact bag count and bulk yardage for your beds, use the mulch calculator and see the dedicated coverage and bag guides below.
FAQs
How deep should mulch be?
2–3 inches for most beds. Deeper than 3–4 inches can block water and air and rot roots; thinner than 2 inches won't suppress weeds.
How often should I add mulch?
Top up to depth once a year, usually in spring. You're refreshing the top inch or so, not adding a full new layer each time.