Mulch Calculator
Find how much mulch you need in cubic yards or bags from the size of your garden beds and the depth you want to spread.
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About the Mulch Calculator
Mulch protects soil, holds moisture and suppresses weeds. This mulch calculator multiplies bed length, width and depth to find the volume in cubic feet and cubic yards, converts it to bags and compares bagged and bulk prices. For curved beds, break the area into rectangles and add the results.
How to use it
- Enter the length and width of the area in feet and the mulch depth in inches.
- Enter the bag size and the prices for bagged and bulk mulch.
- Press Calculate mulch to see cubic yards, bags and cost.
Mulch formula
Cubic feet = length × width × depth in inches ÷ 12. Cubic yards = cubic feet ÷ 27. A 20 × 6 ft bed at 3 inches deep needs 30 cubic feet, or about 1.1 cubic yards.
How deep should mulch be?
| Use | Recommended depth |
|---|---|
| Flower and shrub beds | 2 to 3 inches |
| Around trees | 2 to 4 inches, kept off the trunk |
| Vegetable gardens | 2 to 3 inches |
| Paths | 3 to 4 inches |
Frequently asked questions
How many bags of mulch are in a cubic yard?
About 13.5 bags of 2 cubic foot mulch make one cubic yard (27 cubic feet).
How much mulch do I need for 100 square feet?
At 3 inches deep you need 25 cubic feet, about 0.93 cubic yards or 13 bags of 2 cubic feet.
Is bulk mulch cheaper than bags?
Usually yes for larger jobs, though delivery may add a fee. Compare per cubic yard.
How deep should I spread mulch?
Two to three inches for most beds. Deeper mulch can suffocate roots and attract pests.
Do I include waste?
Add 5% to 10% for uneven ground and settling.
Last reviewed: November 2026.