Mulch Calculator
Calculate how many cubic yards or bags of mulch you need for a garden bed. Enter the bed size and mulch depth to get cubic yards, 2 cu ft bags and 3 cu ft bags.
By CalcBuilt Editorial TeamUpdated September 9, 2026Formulas checked against manufacturer specs, see how we calculate.
Results
- Mulch needed
- 0.93 cu yd
- 25 cu ft
- 2 cu ft (56 L) bags
- 13 bags
- 3 cu ft (85 L) bags
- 9 bags
- Area covered
- 100 sq ft
- At 3 in deep
Mulch formula
Cubic feet = Length (ft) x Width (ft) x Depth (in) / 12
Cubic yards = Cubic feet / 27
Bags = Cubic feet / bag size (2 or 3 cu ft per bag)Worked example
Three beds each 15 x 4 ft mulched 3 in deep: 15 x 4 x 0.25 x 3 = 45 cubic feet, or 1.67 cubic yards. That is 23 bags of 2 cu ft or 15 bags of 3 cu ft. At $40 per yard in bulk, about $67 of mulch plus delivery.
Quick reference
| Depth | Sq ft covered per cubic yard | Cubic yards per 1,000 sq ft |
|---|---|---|
| 1 in | 324 | 3.1 |
| 2 in | 162 | 6.2 |
| 3 in | 108 | 9.3 |
| 4 in | 81 | 12.3 |
| 6 in | 54 | 18.5 |
How to calculate mulch
Multiply the bed length by width in feet, then by the depth in feet (inches divided by 12). That gives cubic feet. Divide by 27 for cubic yards. A 20 by 5 foot bed at 3 inches deep needs 25 cubic feet, or just under one cubic yard.
One cubic yard of mulch covers 108 square feet at 3 inches deep, 162 square feet at 2 inches, and 81 square feet at 4 inches.
Bags or bulk?
Bagged mulch is convenient for anything under about 2 cubic yards. Beyond that, bulk delivery is usually half the price per yard. A cubic yard is 13.5 bags of 2 cubic feet or 9 bags of 3 cubic feet.
For established beds that already have mulch, 1 to 2 inches of fresh mulch is enough to refresh the color and top up what has decomposed.
Key facts
- One cubic yard of mulch covers 108 sq ft at 3 in deep, 162 sq ft at 2 in, and 81 sq ft at 4 in.
- A cubic yard equals 13.5 bags of 2 cu ft or 9 bags of 3 cu ft.
- The recommended depth is 2 to 3 in for garden beds and up to 4 in for weed suppression on bare soil.
- Bulk mulch typically costs $30 to $60 per cubic yard; bagged mulch costs roughly twice as much per yard.
Frequently asked questions
How many bags of mulch are in a cubic yard?
13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet.
How many square feet does a yard of mulch cover?
About 108 square feet at 3 inches deep, 162 square feet at 2 inches, or 81 square feet at 4 inches.
How deep should mulch be?
2 to 3 inches for most garden beds. Go up to 4 inches over bare soil for weed control, but keep mulch a few inches away from plant stems and tree trunks.
Sources and references
- Mulch factsheet HGIC 1604: types and recommended depth (Clemson Cooperative Extension)
- Mulching Landscape Trees: 2 to 4 inch depth guidance (Penn State Extension)
- Edging and Mulching Landscape Beds (University of Illinois Extension)
Next steps for this project
The usual order for a landscaping & outdoor project. See all landscaping & outdoor calculators.
Results are estimates based on standard formulas and typical product specifications. Confirm quantities with your supplier and local code before ordering.