Updated July 18, 2026
How it works
Volume = area × depth (÷ 12 to convert inches to feet). We then convert to cubic yards for bulk orders (÷ 27) and to standard 2-cubic-foot bags (÷ 2).
Depth and coverage figures below track University of Minnesota Extension and Clemson HGIC guidance for garden beds, cited further down.
What a yard of mulch actually covers
A cubic yard of mulch covers about 162 square feet at 2 inches deep, or 108 square feet at 3 inches. That same yard equals 13.5 standard 2-cubic-foot bags, so the calculator gives you both numbers and you pick whichever way you are buying.
University extension programs recommend a 2 to 4 inch layer for most beds, with 2 to 3 inches the usual sweet spot. Less than that and weeds push through; more than 4 inches can starve roots of air and hold too much water against the soil.
Coverage per cubic yard
| Depth | Coverage per yard | 2-cu-ft bags per yard |
|---|---|---|
| 1″ | about 324 ft² | 13.5 |
| 2″ | about 162 ft² | 13.5 |
| 3″ | about 108 ft² | 13.5 |
The bag count per yard does not change with depth; depth only changes how far that yard spreads. A cubic yard is always 27 cubic feet, which is 13.5 of the 2-cubic-foot bags most retailers sell.
Worked example
Say you have a 200 square foot bed and want 3 inches of mulch. Convert depth to feet: 3 ÷ 12 = 0.25 ft. Then:
- Cubic feet: 200 × 0.25 = 50 ft³
- Cubic yards: 50 ÷ 27 = about 1.85 yd³
- Bags: 50 ÷ 2 = 25 bags
So either about 2 yards bulk or 25 bags. Above roughly 10 cubic yards, bulk delivery usually beats bagged on price; below that, bags are easier to haul and store.
Tips from the field
- Keep mulch off stems and trunks. Piling it into a volcano against bark traps moisture and invites rot and pests.
- Refresh, do not just pile on. Organic mulch breaks down over 1 to 2 years; fluff what is there and top up thin spots rather than building an ever-deeper crust.
- Measure the bed, not the yard. Use the square footage tool for odd shapes so you are not guessing.
- Time it right. Late spring once the soil warms holds summer moisture; a fall layer protects roots through winter.
Sources: UMN Extension, Clemson HGIC.
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