Work out how much mulch you need for your garden beds in cubic yards or bags. Enter the bed size and mulch depth, and this mulch calculator shows yards, bags and cost.
How to calculate mulch
Cubic yards = Length (ft) × Width (ft) × Depth (in) ÷ 12 ÷ 27
Or the quick way: square feet × depth in inches ÷ 324.
Example
Two flower beds of 20 × 4 ft each (160 sq ft) mulched 3 inches deep: 160 × 3 ÷ 324 = 1.48 cubic yards, or about 20 bags of 2 cu ft mulch.
How deep should mulch be?
Most garden guides recommend 2 to 3 inches for beds. Deeper mulch can keep soil too wet and limit air to the roots. Keep mulch a few inches away from tree trunks and plant stems.
Mulch coverage chart
| 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 |
Bags vs. bulk mulch
One cubic yard equals 13.5 bags of 2 cu ft or 9 bags of 3 cu ft. Bags are easy for small jobs; bulk delivery is usually cheaper for large areas.
Frequently asked questions
How much does a yard of mulch weigh?
Roughly 400–800 lb, depending on the wood and how wet it is. The calculator uses 0.4 tons (800 lb) as a default; change it if your supplier gives a different figure.
How often should I add mulch?
Organic mulch breaks down, so many gardeners top it up about once a year to keep a 2–3 inch layer.