Enter the size of the bed and how deep you want the mulch. The calculator shows the volume in cubic yards for bulk delivery and the number of bags for the bag size you pick.
How the mulch calculator works
- Volume = length × width × depth. One cubic yard is 27 cubic feet.
- Bags = volume ÷ bag size, rounded up. Most garden-center bags hold 2 or 3 cubic feet.
- Extra is 0% by default. Add a few percent if the mulch is fluffy and will settle.
Worked example
A 10 × 20 ft bed at 3 in deep needs 200 × 3 ÷ 12 = 50 cu ft of mulch. That is 1.85 cubic yards, 25 bags of 2 cu ft or 17 bags of 3 cu ft.
Mulch per 100 square feet
| Depth | Cubic feet | Cubic yards | 2 cu ft bags | 3 cu ft bags |
|---|---|---|---|---|
| 1 in | 8.3 | 0.31 | 5 | 3 |
| 2 in | 16.7 | 0.62 | 9 | 6 |
| 3 in | 25.0 | 0.93 | 13 | 9 |
| 4 in | 33.3 | 1.23 | 17 | 12 |
One cubic yard covers about 324 sq ft at 1 in, 162 sq ft at 2 in, 108 sq ft at 3 in and 81 sq ft at 4 in.
Step by step: mulching a bed
Tips before you order
- Top up existing mulch by only an inch or so each year rather than adding the full depth again.
- Volcano-shaped mounds of mulch against tree trunks can cause rot. Keep a gap around the base.
- Weed and water the bed before you spread mulch.
- Bag sizes are on the front of the bag. Pick the matching size in the calculator.
