Mulch Calculator
Add each bed or tree ring, pick a depth and get cubic yards and bags of mulch, plus an optional bulk vs bags cost comparison.
How deep should mulch be?
Extension services recommend about 2–3 inches for fine-textured mulch and 3–4 inches for coarse mulch such as wood chips or bark nuggets. That is enough to hold moisture and suppress weeds. Deeper layers can keep the soil too wet and starve roots of air, so when refreshing an existing layer usually only about 1 inch is needed.
Keep mulch off trunks and stems. Leave a few inches of bare ground around the base of trees and shrubs; mulch piled against the bark (“volcano mulching”) holds moisture against it and invites rot and pests. Use the Ring shape in the calculator for a mulch ring: enter the outer diameter and the bare circle around the trunk as the inner diameter.
Mulch types
Shredded hardwood, pine bark, cedar and wood chips are sold by the cubic yard or in 2 and 3 cu ft bags and are what this calculator is for. Straw and pine needles are lighter seasonal mulches. Rubber and stone mulch are sold by weight; for stone, use the gravel calculator.
Worked example
Three beds of 4 × 20 ft plus five tree rings 6 ft across with a 1 ft bare circle, all at 3 inches: beds 240 sq ft, rings 5 × 27.5 = 137 sq ft, total 377 sq ft × 3 ÷ 12 = 94 cu ft = 3.5 cu yd. That is about 48 bags of 2 cu ft or 32 bags of 3 cu ft.
How much does one cubic yard cover?
A cubic yard is 27 cubic feet, so at 1 inch deep it covers 324 sq ft. Divide 324 by the depth in inches:
| Depth | 1 cu yd of mulch covers |
|---|---|
| 1 in | 324 sq ft |
| 2 in | 162 sq ft |
| 3 in | 108 sq ft |
| 4 in | 81 sq ft |
| 6 in | 54 sq ft |
| 12 in | 27 sq ft |
Bags per cubic yard
| Bag size | Bags of mulch in 1 cu yd |
|---|---|
| 1.5 cu ft | 18 |
| 2 cu ft | 13.5 |
| 3 cu ft | 9 |
Past about one cubic yard, bulk delivery is usually cheaper and much less carrying than bags; compare both with the optional price fields above.
Common questions
How many bags of mulch are in a yard?
13.5 bags of 2 cu ft, or 9 bags of 3 cu ft.
How much area does a yard of mulch cover?
About 162 sq ft at 2 inches, 108 sq ft at 3 inches and 81 sq ft at 4 inches.
How much mulch do I need around a tree?
Use the Ring shape: outer diameter of the mulched circle and a small inner bare circle. A 6 ft ring with a 1 ft gap at 3 inches is about 6.9 cu ft, roughly 3.5 bags of 2 cu ft.
How much does a yard of mulch weigh?
Shredded wood mulch is light, typically about 400–800 lb per cubic yard (0.2–0.4 tons), depending on the wood and moisture.
Should I remove old mulch first?
Not usually. If the old layer is still 2 inches or more, add only enough to bring it back to 2–4 inches in total.
Sources
- University of Illinois Extension: Proper mulching techniques
- Penn State Extension: Mulching landscape trees
- Rutgers NJAES FS099: Mulching for a healthy landscape
Other calculators
Last updated 2026-09-19.