How to Calculate How Much Mulch You Need
The formula is straightforward: multiply your area in square feet by the depth in inches, then divide by 324 to get cubic yards. Or use the calculator above and skip the math.
Formula:
Cubic Yards = (Length × Width × Depth in inches) ÷ 324
Example: 10 ft × 20 ft bed, 3 inches deep
(10 × 20 × 3) ÷ 324 = 1.85 cubic yards
How Many Cubic Feet in a Yard of Mulch?
One cubic yard contains exactly 27 cubic feet (3 ft × 3 ft × 3 ft = 27 ft³). This conversion matters when you're comparing bulk mulch (sold by the yard) to bagged mulch (sold in cubic feet).
How Many Bags of Mulch in a Yard?
The most common bag size is 2 cubic feet. Since 1 yard = 27 cubic feet:
| Bag Size | Bags per Yard | Common at |
|---|---|---|
| 1.5 cu ft | 18 bags | Lowe's |
| 2 cu ft | 13.5 bags (round up to 14) | Home Depot, most stores |
| 3 cu ft | 9 bags | Premium brands |
Bulk vs. Bagged Mulch: Which Is Cheaper?
Bulk mulch is almost always cheaper for areas over 200–300 sq ft. A cubic yard of bulk mulch costs $25–$50, while the same volume in 2 cu ft bags costs $47–$81 (at $3.50–$6 per bag). For smaller beds or when delivery isn't practical, bagged mulch is the convenient choice.
Common Mulching Mistakes to Avoid
- ✗Volcano mulching: Piling mulch against a tree trunk causes rot and pest damage. Keep a 3–6 inch gap.
- ✗Too thin: Less than 2 inches doesn't suppress weeds effectively. 3 inches is the sweet spot.
- ✗Too thick: More than 4 inches can suffocate roots and prevent rainfall from reaching soil.
- ✗Wrong material: Fine mulch compacts and blocks water. Use shredded bark for beds, wood chips for paths.