How to calculate mulch
Bags = Cubic feet ÷ bag size (2 or 3 ft³)
For an irregular bed, split it into rectangles and circles, add up the areas, then enter the total using “I know the square feet”.
Worked example
A bed 20 ft by 10 ft, mulched 3 in deep: 200 × 3 ÷ 12 = 50 cubic feet. That is 1.85 cubic yards, or 25 bags of 2 cubic feet.
Mulch coverage chart
| Depth | 1 cubic yard covers | One 2 ft³ bag covers | One 3 ft³ bag covers |
|---|---|---|---|
| 1 in | 324 sq ft | 24 sq ft | 36 sq ft |
| 2 in | 162 sq ft | 12 sq ft | 18 sq ft |
| 3 in | 108 sq ft | 8 sq ft | 12 sq ft |
| 4 in | 81 sq ft | 6 sq ft | 9 sq ft |
How deep should mulch be?
- 2 in for topping up an existing layer or fine mulches.
- 3 in for most flower beds and shrub borders. It blocks weeds while letting water through.
- 4 in for coarse wood chips or areas with heavy weed pressure.
More than 4 in can keep soil too wet and starve roots of oxygen. Keep mulch 2–3 in away from tree trunks and plant stems, and avoid piling it up in a cone around trees.
Bags or bulk?
A cubic yard equals 13.5 bags of 2 cubic feet or 9 bags of 3 cubic feet. Bulk mulch is usually cheaper once you need more than 2–3 yards, though delivery fees vary. Bags are easier to carry to the back yard and store neatly.
Frequently asked questions
How many bags of mulch are in a yard?
One cubic yard is 27 cubic feet: 13.5 bags of 2 cubic feet or 9 bags of 3 cubic feet.
How much area does a bag of mulch cover?
A standard 2 cubic foot bag covers about 12 sq ft at 2 in deep, or 8 sq ft at 3 in deep.
How much mulch do I need around a tree?
For a ring 6 ft across at 3 in deep, you need about 7 cubic feet of mulch, roughly 4 bags of 2 cubic feet. Choose the circle option above and enter your diameter.
Should I remove old mulch first?
Not usually. Rake old mulch to loosen it and top up to a total of 2–3 in. Remove it only if it is matted, moldy or already deeper than 3 in.
Last reviewed 2026-11-14. Material weights are typical industry averages and vary by supplier, moisture and compaction.