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Mulch Calculator: Square Feet to Cubic Yards
Enter your bed's square footage and how deep you want the mulch layer. This tool converts that to cubic yards, bag count, and a rough cost estimate.
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How the math works
Mulch is sold by volume, same as concrete or gravel. The calculation:
cubic yards = cubic feet ÷ 27
bags needed = cubic feet ÷ 2 (standard bag size)
Depth needs to be converted from inches to feet before multiplying — divide your depth in inches by 12. Most retail mulch bags hold 2 cubic feet, so dividing your total cubic feet by 2 gives you the bag count.
Coverage reference
| 1 cubic yard covers… | At this depth |
|---|---|
| 324 sq ft | 1" |
| 162 sq ft | 2" |
| 108 sq ft | 3" |
| 81 sq ft | 4" |
Common mistakes
The most common overspend: buying bagged mulch for a large bed when bulk delivery would have been cheaper per yard — bulk typically wins past roughly 2–3 cubic yards, though you'll need somewhere to have it dumped and a way to haul it. The most common underbuy: guessing depth instead of measuring, which leaves a bed that looks thin within a season as mulch settles and breaks down.
Frequently asked questions
How deep should mulch be in a garden bed?
Most garden beds do well with 2 to 3 inches of mulch. Less than that breaks down too fast to suppress weeds; more than 4 inches can suffocate roots and hold too much moisture against plant stems.
How many bags of mulch are in a cubic yard?
About 13.5 standard 2 cubic foot bags make one cubic yard, since a cubic yard equals 27 cubic feet.
Is bulk or bagged mulch cheaper?
Bulk mulch is almost always cheaper per cubic yard than bagged mulch once you need more than roughly 2 to 3 cubic yards, but it usually requires a truck or trailer to haul and a place to dump it.