How Much Mulch Do I Need? (Yards, Bags & Coverage)
To find how much mulch you need, multiply bed length × width for the area, multiply by depth in feet, and divide by 27 for cubic yards. One cubic yard covers about 108 sq ft at 3 inches deep, or roughly 13.5 standard 2-cubic-foot bags. For beds over about a cubic yard, bulk delivery is much cheaper than bags.
Mulch is one of the easiest things to under-buy, because a thin-looking bed swallows far more than people expect once you spread it 2–3 inches deep. Measuring first — and knowing how coverage changes with depth — saves you repeat trips and money.
This guide shows how to calculate mulch in cubic yards and bags, the ideal depth for weed control and moisture, and a coverage chart so you order exactly what your beds need.
Key takeaways
- Mulch (yd³) = bed area × depth (ft) ÷ 27.
- One cubic yard covers ~108 ft² at 3 inches deep.
- It takes ~13.5 standard 2-ft³ bags to equal one cubic yard.
- Aim for 2–3 inches deep; 1 inch for a seasonal refresh.
- Bulk delivery beats bags for anything over a cubic yard.
Skip the math
Get instant numbers with the Mulch Calculator.
How to calculate mulch
Measure each bed's length and width in feet and multiply for the area. Multiply by the depth you want, converted to feet (3 inches = 0.25 ft), to get cubic feet. Divide by 27 for cubic yards, the unit bulk mulch is sold in. For example, a 20 × 10 ft bed at 3 inches is 200 × 0.25 = 50 cubic feet, or about 1.85 cubic yards.
Pick the right depth
A 2–3 inch layer suppresses weeds and holds moisture without smothering roots. Go deeper than 3–4 inches and you can starve roots of oxygen and trap too much moisture. For a seasonal refresh over existing mulch that's still in good shape, 1 inch of new material is usually enough to restore color and depth.
Mulch coverage chart
| Depth | Coverage per yd³ | Bags (2 ft³) per yd³ |
|---|---|---|
| 1 inch | ~324 ft² | ~13.5 |
| 2 inches | ~162 ft² | ~13.5 |
| 3 inches | ~108 ft² | ~13.5 |
| 4 inches | ~81 ft² | ~13.5 |
Bags vs bulk
- Bagged mulch suits small beds and is easy to transport.
- Bulk delivery is far cheaper per yard once you need more than ~1 yd³.
- One cubic yard equals about 13.5 standard 2-cubic-foot bags.
- Keep mulch a few inches away from trunks and stems to prevent rot.