How to use the Mulch Calculator
Enter the bed length, bed width, depth and bag size and the result appears straight away. Everything runs in your browser, so nothing you type is uploaded.
The formula
US: cubic feet = length × width × depth (in) ÷ 12. Metric: m³ = length × width × depth (cm) ÷ 100
Examples
- 20 ft by 5 ft at 3 in deep, 2 cu ft bags
Mulch needed: 0.93 cubic yards (25 cu ft) Bags of 2 cu ft: 13 Area covered: 100 sq ft
- 30 ft by 10 ft at 2 in deep
Mulch needed: 1.85 cubic yards (50 cu ft) Bags of 2 cu ft: 25 Area covered: 300 sq ft
- 12 ft by 8 ft at 4 in deep, 3 cu ft bags
Mulch needed: 1.19 cubic yards (32 cu ft) Bags of 3 cu ft: 11 Area covered: 96 sq ft
Limitations and assumptions
Coverage varies with how mulch settles. Add 5 to 10% for uneven ground.
Frequently asked questions
How do I calculate how much mulch I need?
Multiply length × width × depth (in feet), then divide by 27 for cubic yards. Depth in inches is divided by 12 first.
How deep should mulch be?
Two to three inches suits most beds. Keep it away from trunks and stems.
How many bags make a cubic yard?
A cubic yard is 27 cubic feet, so 13.5 bags of 2 cu ft each.
Should I buy extra?
A small allowance of five to ten percent covers uneven ground and settling.