Mulch and soil calculator
One cubic yard of mulch covers about 108 sq ft at 3 in deep. A 10 x 20 ft bed at 3 in needs 50 cubic feet: 1.85 cubic yards, 25 bags of 2 cu ft or 17 of 3 cu ft. Iowa State Extension suggests 3-4 in on well-drained soil, 2-3 in on heavy soil.
Updated · By the Interior Redesign AI editorial team · Sources cited on the page
Mulch needed
1.85 cu yd
200 sq ft at 3 in deep.
2 cu ft bags
25
the common small bag
3 cu ft bags
17
the common large bag
| Area | 200 sq ft |
|---|---|
| Volume (area × depth) | 50 cu ft |
| Cubic yards (÷ 27) | 1.85 cu yd |
- OKWithin Iowa State Extension's range: 3-4 in on well-drained sites, 2-3 in on heavy soils. Keep it 6 in back from tree trunks.
Bulk mulch is sold by the cubic yard; bags by cubic feet.
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Key numbers
- Mulch depth, well-drained sites
- 3-4 in of wood chips or shredded bark (Iowa State Extension)
- Mulch depth, heavy soils
- 2-3 in (Iowa State Extension)
- Around trees
- Keep mulch at least 6 in from the trunk (Iowa State Extension)
- One cubic yard
- 27 cu ft: 108 sq ft at 3 in, 162 sq ft at 2 in, 81 sq ft at 4 in
- Bags per cubic yard
- 13.5 bags of 2 cu ft, 9 bags of 3 cu ft
Worked example
A 10 x 20 ft bed at 3 in
One rectangular bed of shredded bark mulch, 3 in deep.
- Area: 20 × 10 = 200 sq ft.
- Volume: 200 × 3 ÷ 12 = 50 cu ft.
- Cubic yards: 50 ÷ 27 = 1.85.
- Bags: 50 ÷ 2 = 25 small bags, or 50 ÷ 3 = 17 large bags (rounded up).
Order 1.9 cubic yards in bulk, or buy 25 bags of 2 cu ft.
How we calculate
Volume is the bed area times the depth: square feet × inches ÷ 12 gives cubic feet, and cubic feet ÷ 27 gives cubic yards, the unit bulk mulch and soil are sold in. Bags are the volume divided by the bag size, rounded up. Circles (tree rings) use π × radius².
The mulch depth default of 3 in sits in Iowa State Extension's range: 3-4 in on well-drained sites, 2-3 in on heavy soils. The calculator flags depths outside 2-4 in.
Assumptions, labeled: the 4 in default for topsoil and 2 in for compost are our starting points, not standards. Set the depth your project needs, such as a lawn patch, a raised bed or a top-dressing. Fresh, fluffy material settles, so many people buy a little extra.
Estimates, sources
Planning estimates and published guidelines, not quotes, designs or code rulings. Figures were checked on each source on the date shown. Local prices, your home and your jurisdiction's adopted code decide the real answer.
- How deep should the mulch layer be around trees and shrubs? (Iowa State University Extension and Outreach, as of Oct 26, 2026): 3 to 4 in of wood chips or shredded bark on well-drained sites, 2 to 3 in on heavy soils; keep mulch at least 6 in from tree trunks (undated page)
How far a cubic yard goes
A 6 ft tree ring at 3 in takes 7.1 cu ft, 4 small bags. For bigger beds, a cubic yard covers:
| Depth | Area one cubic yard covers | 2 cu ft bags per 100 sq ft |
|---|---|---|
| 1 in | 324 sq ft | 5 |
| 2 in | 162 sq ft | 9 |
| 3 in | 108 sq ft | 13 |
| 4 in | 81 sq ft | 17 |
| 6 in | 54 sq ft | 25 |
How to use this tool
Pick the material
Mulch, topsoil or compost; each starts with its own default depth.
Measure the bed
Length and width, or the diameter for a tree ring, and how many beds that size.
Set the depth
Iowa State Extension suggests 3-4 in of mulch on well-drained sites, 2-3 in on heavy soils.
Read the order
Cubic yards for bulk delivery and the count of 2 and 3 cu ft bags.
Questions
How much area does a yard of mulch cover?
About 108 sq ft at 3 in deep, 162 sq ft at 2 in and 81 sq ft at 4 in. A cubic yard is 27 cu ft.
How many bags of mulch are in a yard?
13.5 bags of 2 cu ft, or 9 bags of 3 cu ft.
How deep should mulch be?
Iowa State Extension suggests 3-4 in of wood chips or shredded bark on well-drained sites and 2-3 in on heavy soils. Deeper layers can keep roots too wet.
Should mulch touch the tree trunk?
No. Iowa State Extension recommends keeping mulch at least 6 in away from the trunks of trees; piling it against the bark invites rot and pests.
How much topsoil do I need?
Area × depth ÷ 12 gives cubic feet; divide by 27 for cubic yards. At 4 in deep, a yard of topsoil covers 81 sq ft. Pick the depth your project needs.
Is bulk or bagged mulch cheaper?
It depends on local prices and delivery fees. Compare your supplier's price per cubic yard with the bag price times the bags per yard (13.5 of 2 cu ft, 9 of 3 cu ft).
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