Choose your bed shape, enter its size and how deep you want the mulch, and see how many cubic yards and bags to buy. Works in US units or metric.
Mulch Calculator
Estimates only. Check with your supplier before you order, and always buy a little extra.
How to calculate mulch
- Find the area. Rectangle: length × width. Circle: 3.14 × radius × radius (the radius is half the diameter).
- Multiply by the depth in feet. Divide the depth in inches by 12. For 3 inches, that is 0.25 ft.
- Convert to cubic yards. Divide cubic feet by 27.
Mulch (cubic yards) = area (sq ft) × depth (in) ÷ 12 ÷ 27
Example: a 20 × 3 ft border, 3 inches deep
- Area: 20 × 3 = 60 sq ft
- Volume: 60 × 3 ÷ 12 = 15 cubic feet
- 15 ÷ 27 = about 0.56 cubic yards
- In 2 cu ft bags: 15 ÷ 2 = 7.5, so 8 bags
How far does mulch go?
| Depth | 1 cubic yard covers | One 2 cu ft bag covers |
|---|---|---|
| 1 inch | 324 sq ft | 24 sq ft |
| 2 inches | 162 sq ft | 12 sq ft |
| 3 inches | 108 sq ft | 8 sq ft |
| 4 inches | 81 sq ft | 6 sq ft |
Mulching tips
- How deep? A layer of about 2–3 inches is a common recommendation for most beds. Very fine mulch can be a little thinner; coarse bark can be a little deeper.
- Keep it off stems and trunks. Leave a small gap around plant stems and tree trunks. Mulch piled against them holds moisture where it can cause rot.
- Topping up? Measure only the depth you are adding, not the total.
- Bags or bulk? For a cubic yard or more, bulk mulch is often cheaper. A cubic yard is about 13.5 bags of 2 cu ft.
Frequently asked questions
How much mulch do I need for 100 square feet?
At 3 inches deep, 100 sq ft needs 25 cubic feet: about 0.93 cubic yards, or 13 bags of 2 cu ft.
How many bags of mulch are in a yard?
A cubic yard is 27 cubic feet, so about 13.5 bags of 2 cu ft or 9 bags of 3 cu ft.
How do I measure an irregular bed?
Split it into rough rectangles and circles, work out each area, add them up and choose “I know the area” in the calculator.