How Much Mulch Do I Need?
By Nick · Updated
Multiply the bed's square feet by the depth in inches, then divide by 324 to get cubic yards. A 200 square foot bed at 3 inches needs 1.85 cubic yards, or 25 bags of 2 cubic feet. Garden beds need 2 to 3 inches.
Measure your own bedsKey figures
- Spread 2 to 3 inches of mulch on garden beds.
Source: University of Illinois Extension (2018); UF/IFAS Florida-Friendly Landscaping
- Square feet × inches ÷ 324 = cubic yards (324 = 27 cubic feet × 12 inches).
- One cubic yard covers 162 square feet at 2 inches, or 108 at 3 inches.
How deep should mulch be?
2 to 3 inches on garden beds.
Both the University of Illinois and the University of Florida give the same range.
Source: University of Illinois Extension (2018); UF/IFAS Florida-Friendly Landscaping
How do you work out how much mulch you need?
Find the square feet, multiply by the depth in inches, and divide by 324.
For a 10 × 20 ft bed at 3 inches:
- Area: 10 × 20 = 200 square feet
- Cubic yards: 200 × 3 ÷ 324 = 1.85
- Bags: 50 cubic feet ÷ 2 = 25 bags of 2 cubic feet
For curved or odd beds, split them into rectangles, circles and triangles and add the areas up.
How much mulch goes around a tree?
A 6-foot-wide ring at 3 inches deep takes 7.1 cubic feet: 4 bags of 2 cubic feet.
A circle's area is 3.14 × the radius squared. A 6 ft ring has a 3 ft radius, so it covers 28.3 square feet.
How much mulch do common bed sizes need?
Cubic yards and 2 cubic foot bags, at 2 and 3 inches deep:
| Bed size | At 2 in | At 3 in |
|---|---|---|
| 50 sq ft | 0.31 cu yd · 5 bags | 0.46 cu yd · 7 bags |
| 100 sq ft | 0.62 cu yd · 9 bags | 0.93 cu yd · 13 bags |
| 200 sq ft | 1.23 cu yd · 17 bags | 1.85 cu yd · 25 bags |
| 500 sq ft | 3.09 cu yd · 42 bags | 4.63 cu yd · 63 bags |
| 1,000 sq ft | 6.17 cu yd · 84 bags | 9.26 cu yd · 125 bags |
Other questions
How much does a yard of mulch cover?
162 square feet at 2 inches deep and 108 square feet at 3 inches.
How many bags of mulch do I need for 100 square feet?
13 bags of 2 cubic feet at 3 inches, or 9 bags at 2 inches.
How we worked this out
Volumes are square feet × depth, converted with 27 cubic feet per cubic yard. Bag counts are rounded up to whole bags. Every figure is calculated by the same code as the mulch calculator.
Sources
- University of Illinois Extension (2018)
- UF/IFAS Florida-Friendly Landscaping
- Vigoro and Scotts mulch, 2 cu ft bags (Home Depot listing)
- NIST Handbook 44 (2024), Appendix C