How to use the mulch calculator
- Measure each bed's length and width. For round tree rings, choose Circle and enter the diameter. For odd-shaped beds, estimate the square feet or split them into rectangles and add the results.
- Choose a depth. 2–3 inches is right for most beds; 3–4 inches for weed suppression on bare ground.
- Read off cubic yards if you're buying bulk, or the number of bags if you're buying bagged mulch.
Mulch formula
cubic feet = area (sq ft) × depth (in) ÷ 12
cubic yards = cubic feet ÷ 27
2 cu ft bags = cubic feet ÷ 2
One cubic yard of mulch covers about 162 sq ft at 2 inches deep, 108 sq ft at 3 inches, or 81 sq ft at 4 inches. It equals 13.5 bags of 2 cubic feet.
Mulch needed by bed size
| Bed area (sq ft) | Yards at 2 in | 2 cu ft bags at 2 in | Yards at 3 in | 2 cu ft bags at 3 in |
|---|---|---|---|---|
| 50 | 0.31 | 5 | 0.46 | 7 |
| 100 | 0.62 | 9 | 0.93 | 13 |
| 150 | 0.93 | 13 | 1.39 | 19 |
| 200 | 1.23 | 17 | 1.85 | 25 |
| 300 | 1.85 | 25 | 2.78 | 38 |
| 500 | 3.09 | 42 | 4.63 | 63 |
| 1000 | 6.17 | 84 | 9.26 | 125 |
How deep should mulch be?
- Refreshing existing mulch: 1 inch on top of what's there.
- Flower and shrub beds: 2–3 inches.
- New beds or weedy ground: 3–4 inches. Deeper than 4 inches can starve roots of air and water.
- Around trees: 2–4 inches, kept a few inches away from the trunk. Avoid "mulch volcanoes".
Bagged or bulk mulch?
Bulk mulch is usually much cheaper per cubic yard once you need more than 2–3 yards, but there is typically a delivery fee. Bags are easier for small beds, cars without a trailer, and spreading a little at a time.
Frequently asked questions
How many bags of mulch are in a yard?
A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cu ft mulch or 9 bags of 3 cu ft mulch.
How much area does a yard of mulch cover?
About 108 sq ft at 3 inches deep, 162 sq ft at 2 inches deep, and 324 sq ft at 1 inch deep.
How many bags of mulch do I need for 100 square feet?
At 3 inches deep, 100 sq ft needs 25 cubic feet of mulch, which is 13 bags of 2 cu ft (or 9 bags of 3 cu ft).