How much mulch do I need?
A 200-square-foot bed at 3 inches deep takes about 1.9 cubic yards of mulch — or roughly 25 of the standard 2-cubic-foot bags. The rule is simple: multiply the area by the depth and convert. Here's the formula, a chart by bed size, and how deep to spread it.
The formula
Mulch is sold by volume, so you need area and depth:
Cubic yards = bed area (sq ft) × depth (in) ÷ 324
The 324 converts square-feet-inches into cubic yards in one step (a cubic yard is 27 cubic feet, and 27 × 12 = 324). For bags, divide the area by the coverage of one bag: a 2-cubic-foot bag covers about 8 sq ft at 3 inches deep, or 12 sq ft at 2 inches.
Mulch by bed size
At a 3-inch depth, with bags counted as the common 2-cubic-foot size:
| Bed area | Mulch (3″ deep) | 2 cu ft bags |
|---|---|---|
| 100 sq ft | 0.9 cu yd | 13 bags |
| 200 sq ft | 1.9 cu yd | 25 bags |
| 300 sq ft | 2.8 cu yd | 38 bags |
| 500 sq ft | 4.6 cu yd | 63 bags |
| 1,000 sq ft | 9.3 cu yd | 125 bags |
Spreading only 2 inches instead of 3? You'll need about a third less — multiply the numbers above by 0.67.
Odd-shaped bed? Let the calculator do it
The mulch & soil calculator turns your bed size and depth into cubic yards, bags, and cost — and works for mulch, topsoil, or gravel.
Open the Mulch & Soil CalculatorHow deep should mulch be?
- 3 inches on new beds, or anywhere you want real weed suppression and moisture retention.
- 1–2 inches to refresh a bed that still has last year's mulch — top up to about 3 inches total rather than burying it.
- Keep it off the stems. Pull mulch a couple of inches back from plant crowns and tree trunks. A "mulch volcano" piled against bark traps moisture and rots the trunk.
Bags or bulk?
One cubic yard equals about 13.5 bags (27 cu ft ÷ 2). Bagged mulch is convenient and easy to haul in a car, but the price per cubic foot is higher — so once you need more than roughly half a yard (about 7 bags), bulk delivery by the yard is usually cheaper and far less hauling. For a few containers or a small bed, bags win; for a whole front yard, order bulk.
A quick tip on coverage
If you'd rather think in coverage than volume, remember that one cubic yard blankets about 108 sq ft at 3 inches, 162 sq ft at 2 inches, or 324 sq ft at 1 inch. Measure your beds, pick a depth, and divide.