Mulch Calculator
Find out how much mulch you need. Enter your bed's length, width, and depth and this mulch calculator gives you the cubic yards, cubic feet, and number of bags.
Reviewed & updated for 2026 by Rakesh Choudhary, PhD · How we calculate
How deep should mulch be?
Depth drives how much you buy. For most ornamental beds, 2–3 inches is ideal: enough to hold moisture and block weeds without smothering roots. Use 3–4 inches where weeds are aggressive, and keep it lighter (1–2 inches) over shallow roots and a few inches away from tree trunks and plant stems to prevent rot.
Mulch also settles and decomposes, so most gardeners top up about an inch each year rather than starting from scratch.
Coverage per cubic yard
| Depth | 1 cubic yard covers | 2 cu ft bags / yard |
|---|---|---|
| 1 inch | 324 sq ft | 13.5 |
| 2 inches | 162 sq ft | 13.5 |
| 3 inches | 108 sq ft | 13.5 |
| 4 inches | 81 sq ft | 13.5 |
A cubic yard is always 13.5 bags (2 cu ft) regardless of depth; only the area it covers changes.
Mulch needed for common bed sizes
A starting point for a standard 3-inch layer. Bags assume the common 2-cubic-foot size (one bag covers about 8 sq ft at 3 inches deep). Bulk mulch is sold by the cubic yard, which covers roughly 108 sq ft at the same depth:
| Bed size | Cubic yards (3" deep) | 2 cu ft bags |
|---|---|---|
| 50 sq ft | 0.5 | 7 |
| 100 sq ft | 0.9 | 13 |
| 200 sq ft | 1.9 | 25 |
| 300 sq ft | 2.8 | 38 |
| 500 sq ft | 4.6 | 63 |
| 1,000 sq ft | 9.3 | 125 |
For a 2-inch refresh on existing mulch, multiply these amounts by about ⅔; for a deep 4-inch layer, multiply by about 1⅓. The calculator above does the exact math for your bed shape and depth.
FAQs
How much mulch do I need?
Multiply the bed's length × width to get square feet, then multiply by the depth in feet (inches ÷ 12) to get cubic feet. Divide by 27 for cubic yards. For example, a 20 ft × 10 ft bed at 3 inches deep = 200 × 0.25 = 50 cubic feet, or about 1.85 cubic yards. The calculator above does this for you.
How deep should mulch be?
Most landscape beds want 2–3 inches of mulch. Use 3–4 inches for heavy weed suppression or moisture retention, and a thinner 1–2 inches around shallow-rooted plants and trees (keep mulch a few inches off trunks). Deeper than 4 inches can suffocate roots.
How many bags of mulch are in a cubic yard?
One cubic yard equals 27 cubic feet, so it's 13.5 bags of the standard 2-cubic-foot size, or 9 bags of 3-cubic-foot mulch. Buying in bulk by the yard is usually cheaper than bags if you need more than about 10–12 bags.
How much does a cubic yard of mulch cover?
One cubic yard covers about 108 square feet at 3 inches deep, 162 square feet at 2 inches, or 324 square feet at 1 inch. Coverage drops as depth increases, that's why this calculator asks for both your area and your target depth.
Should I buy mulch in bags or bulk?
Bags are convenient for small beds (under ~1 cubic yard) and easy to handle. Bulk delivery by the cubic yard is more economical for larger areas and means less plastic, but you'll need a truck or a delivery fee and somewhere to pile it. The break-even is usually around 10–13 bags.