Quick Answer
Mulch is usually sold by the cubic yard or by the bag. To calculate how much mulch you need, multiply area by depth, then convert to cubic yards.
Cubic yards = Square feet × Depth in inches ÷ 324
For example, a 200 square foot bed at 3 inches deep needs:
200 × 3 ÷ 324 = 1.85 cubic yards
Recommended Mulch Depth
| Use Case | Depth |
|---|---|
| Refresh existing mulch | 1-2 inches |
| New garden bed | 2-3 inches |
| Weed suppression | 3 inches |
| Around trees | 2-4 inches, away from trunk |
| Playground mulch | Follow product safety depth |
Do not pile mulch against tree trunks or plant stems. A thick "mulch volcano" traps moisture and can damage the plant.
Bags vs Cubic Yards
Bagged mulch is convenient for small projects. Bulk mulch is usually better for larger beds.
| Amount | Approximate Equivalent |
|---|---|
| 1 cubic yard | 27 cubic feet |
| 1 cubic yard | about 13.5 bags of 2 cu ft mulch |
| 1 cubic yard | about 9 bags of 3 cu ft mulch |
| 10 bags of 2 cu ft | 20 cubic feet, or 0.74 cubic yards |
How to Measure Irregular Beds
For curved or irregular beds, break the area into smaller rectangles and circles, estimate each part, then add them together. A close estimate is good enough because mulch is usually ordered with a small buffer.
If your bed has large shrubs, rocks, or paths, subtract only the big areas. Small plants do not need to be removed from the estimate.
Key Takeaways
- Use
square feet × depth in inches ÷ 324for cubic yards. - Two to three inches is enough for most garden beds.
- One cubic yard equals 27 cubic feet.
- Bulk mulch is usually easier for larger jobs.
- Keep mulch away from trunks and stems.