Mulch calculator: cubic yards and bags
The short answer
Cubic yards of mulch = square feet x depth in inches / 12, divided by 27. A 4 by 30 foot bed at 3 inches takes about 1.1 cubic yards, or 15 bags of 2 cubic feet.
Mulch calculator
Use this mulch calculator to find the cubic yards, or the number of bags, for a bed or a ring around a tree.
Your numbers
Your answer
About 1.1 cubic yards
You need about 1.1 cubic yards of mulch, or 15 bags of 2 cubic feet.
That covers 120 square feet 3 inches deep (30 cubic feet).
- Cubic yards1.1
- Bags of 2 cu ft15
- Cubic feet30
At a glance
- One cubic yard
- 27 cubic feet
- 1 yard at 3 inches
- Covers 108 sq ft
- 1 yard in 2 cu ft bags
- 14 bags
- Depth on well-drained ground
- 3 to 4 inchesIowa State Extension
How the mulch calculator works
- Find the area in square feet. A rectangle is length x width. A circle is 3.1416 x half the distance across x half the distance across.
- Multiply the area by the depth in feet (inches divided by 12). That is cubic feet.
- Divide the cubic feet by 27 to get cubic yards.
- For bags, divide the cubic feet by the bag size, and round up.
What it assumes
- The same depth all over. If your bed slopes or has low spots, add a little.
- Bag sizes are what is printed on the bag, in cubic feet.
- No extra is added for mulch that settles. Add some if you want it to stay at full depth.
Cubic yards of mulch to bags
Bulk mulch is sold by the cubic yard, and bagged mulch by the cubic foot. One cubic yard is 27 cubic feet.
| Cubic yards | 2 cu ft bags | 3 cu ft bags | Covers at 3 inches |
|---|---|---|---|
| 1 | 14 | 9 | 108 sq ft |
| 2 | 27 | 18 | 216 sq ft |
| 3 | 41 | 27 | 324 sq ft |
| 4 | 54 | 36 | 432 sq ft |
| 5 | 68 | 45 | 540 sq ft |
So 4 yards of mulch is 54 bags of 2 cubic feet. Going the other way, 20 bags of 2 cubic feet cover about 160 square feet at 3 inches deep.
How deep to spread mulch
Iowa State University Extension suggests a 3 to 4 inch layer of wood chips or shredded bark on well-drained ground. On heavy soils, it suggests 2 to 3 inches. The calculator starts at 3 inches.
A Bonners Ferry example
Say you have a flower bed along the front of a house in Bonners Ferry, 30 feet long and 4 feet wide, and you want 3 inches of mulch.
- Area: 30 x 4 = 120 square feet.
- Cubic feet: 120 x 3 / 12 = 30 cubic feet.
- Cubic yards: 30 / 27 = 1.1 cubic yards.
- Bags: 30 / 2 = 15 bags of 2 cubic feet, or 10 bags of 3 cubic feet.
You may not need a pro
Spreading a few yards of mulch is a job for a wheelbarrow and a rake. For a big yard or a set of new beds, a landscaping business can bring it in bulk and spread it.
Facts this tool uses
| Fact | Figure | Source |
|---|---|---|
| Mulch depth on well-drained ground | A 3 to 4 inch layer of wood chips or shredded bark | Iowa State University Extension, How deep should the mulch layer be around trees and shrubs?Depth lines checked Oct 28, 2026 |
| Mulch depth on heavy soils | A 2 to 3 inch layer | Iowa State University Extension, How deep should the mulch layer be around trees and shrubs?Depth lines checked Oct 28, 2026 |
| Space around tree trunks | Keep mulch at least 6 inches away from the trunk | Iowa State University Extension, How deep should the mulch layer be around trees and shrubs?Trunk spacing line checked Oct 28, 2026 |
Next step
Want it delivered and spread? Landscaping in Bonners Ferry