Mulch Calculator
This mulch calculator turns your bed's length, width, and depth into how much mulch you need — cubic yards and 2 ft³ or 3 ft³ bags, with a depth comparison so you can weigh 2" vs 3" vs 4".
Your project
Your materials
Standard industry formulas with waste included. Always confirm quantities with your supplier.
How much mulch do I need?
Multiply your bed's length and width in feet by the depth converted to feet, then divide by 27 to get cubic yards. One cubic yard equals 13.5 of the common 2 ft³ bags or 9 of the larger 3 ft³ bags. Bulk delivery by the yard is usually half the price of bags once you need more than about a yard. Three inches is the sweet spot for most beds — deep enough to suppress weeds, not so deep it suffocates roots.
Worked example. A 20 ft × 5 ft bed at 3 inches deep is 20 × 5 × (3 ÷ 12) = 25 ft³, or 25 ÷ 27 ≈ 0.93 cubic yards. That's about 13 of the standard 2 ft³ bags or 9 of the 3 ft³ bags. Since you're right at a yard, a single bulk scoop delivered is usually cheaper than 13 bags hauled home.
| Depth | Coverage per yd³ | Coverage per 2 ft³ bag |
|---|---|---|
| 1 in | ~324 ft² | ~24 ft² |
| 2 in | ~162 ft² | ~12 ft² |
| 3 in | ~108 ft² | ~8 ft² |
| 4 in | ~81 ft² | ~6 ft² |
One cubic yard = 13.5 bags of 2 ft³ or 9 bags of 3 ft³. Three inches suits most beds.