About this calculator
The Mulch Calculator tells you how much mulch to buy for flower beds, tree rings and garden borders. It gives the volume in cubic yards for bulk delivery and the number of bags for store-bought mulch.
How to calculate how much mulch you need
- Measure each bed. Enter length and width, or choose Circle for a round bed or tree ring.
- Set the depth. Most beds use 2 to 3 inches.
- Pick your bag size to see how many bags to buy, or use the cubic yard figure for bulk.
- Add a price per bag or per cubic yard to estimate the cost.
The mulch formula
Cubic feet = area (sq ft) × depth (ft). Divide by 27 for cubic yards, or by the bag size for bags.
Example: a 100 sq ft bed at 3 inches deep needs 100 × 0.25 = 25 cubic feet. That is 0.93 cubic yards, or 13 bags of 2 cubic feet.
How far does a cubic yard of mulch go?
| Depth | Area covered by 1 cubic yard |
|---|---|
| 2 in | 162 sq ft |
| 3 in | 108 sq ft |
| 4 in | 81 sq ft |
| 6 in | 54 sq ft |
Coverage by bag size
| Bag size | At 2 in | At 3 in | At 4 in |
|---|---|---|---|
| 2 cubic feet | 12 sq ft | 8 sq ft | 6 sq ft |
| 3 cubic feet | 18 sq ft | 12 sq ft | 9 sq ft |
Things to watch out for
- Do not pile mulch against trunks or walls. Leave a gap around tree trunks and house siding.
- Mulch settles. The small waste allowance covers settling and uneven ground.
- Irregular beds. Split them into rectangles and circles, calculate each, and add the results.
- Bulk or bags. For large areas bulk delivery is often better value, but delivery fees and minimums vary, so compare local prices.
Frequently asked questions
A cubic yard is 27 cubic feet. That is 13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet.
Most garden beds use 2 to 3 inches. Thicker layers can hold too much moisture and are usually not needed.
About 108 square feet at 3 inches deep, 162 square feet at 2 inches and 81 square feet at 4 inches.
Break it into rectangles and circles, work out each section, and add the cubic yards together.
A 5 percent allowance covers settling and uneven ground. Use 10 percent if the bed is very uneven.