Home › Mulch calculator · Updated November 4, 2026 · Sources
Mulch Calculator
Enter the length, width and depth of your bed. The ticket gives you the cubic yards for a bulk order and the number of 2 ft³ bags, with a drawing of the bed to check against.
How much area mulch covers
| Depth | One cubic yard covers | One 2 ft³ bag covers |
|---|---|---|
| 1 in | 324 ft² | 24.0 ft² |
| 2 in | 162 ft² | 12.0 ft² |
| 3 in | 108 ft² | 8.0 ft² |
| 4 in | 81 ft² | 6.0 ft² |
Mulch for common bed sizes
Cubic yards and 2 ft³ bags, before any extra.
| Bed | 2 in deep | 3 in deep | 4 in deep |
|---|---|---|---|
| 4 × 10 ft | 0.25 yd³ · 4 bags | 0.37 yd³ · 5 bags | 0.49 yd³ · 7 bags |
| 3 × 20 ft | 0.37 yd³ · 5 bags | 0.56 yd³ · 8 bags | 0.74 yd³ · 10 bags |
| 5 × 20 ft | 0.62 yd³ · 9 bags | 0.93 yd³ · 13 bags | 1.23 yd³ · 17 bags |
| 10 × 10 ft | 0.62 yd³ · 9 bags | 0.93 yd³ · 13 bags | 1.23 yd³ · 17 bags |
| 10 × 20 ft | 1.23 yd³ · 17 bags | 1.85 yd³ · 25 bags | 2.47 yd³ · 34 bags |
| 20 × 20 ft | 2.47 yd³ · 34 bags | 3.70 yd³ · 50 bags | 4.94 yd³ · 67 bags |
Worked examples
- Ring around a tree, 6 ft across, 3 in deep: 0.26 yd³, or 4 bags. Keep the mulch pulled back from the trunk.
- Front bed, 20 × 5 ft, 3 in deep: 0.93 yd³, or 13 bags.
- Border along a fence, 50 × 4 ft, 3 in deep: 1.85 yd³, or 25 bags. At this size a bulk delivery is usually worth pricing.
How deep to spread mulch
- Most beds: 2–3 in. Mississippi State University Extension says that's enough for most uses; Gardening Know How gives 2–4 in.
- Topping up: add a thin new layer rather than a full depth each year, so the total doesn't creep up as old mulch breaks down.
- Around trees and shrubs: spread it outward like a bowl and keep it off the trunk. Piled-up "mulch volcanoes" hold moisture against the bark.
- Too deep: 10 in is far too much and can stop water reaching the soil.
The formula
Cubic yards = length (ft) × width (ft) × depth (in ÷ 12) ÷ 27
Bags (2 ft³) = length (ft) × width (ft) × depth (in ÷ 12) ÷ 2
For a round bed, area = 3.14 × radius². For odd shapes, split the bed into rectangles and add them up. Measure along the curve of a border, not straight across.
Bags or bulk?
A cubic yard is 13.5 bags of 2 ft³. Bags suit small beds and cars; a pickup bed or a delivery suits anything over a couple of yards. Mulch is light (about 0.2–0.4 tons per cubic yard), so it's sold by volume, not weight: order the cubic yards on the ticket.
Questions
How many bags of mulch make a cubic yard?
Thirteen and a half 2 ft³ bags, since a cubic yard is 27 ft³ (Gardening Know How). Most bagged mulch is sold in 2 ft³ bags; check the bag, as some hold 1.5 or 3 ft³.
How much area does a bag of mulch cover?
A 2 ft³ bag covers about 12.0 ft² at 2 in deep and 8.0 ft² at 3 in.
How much area does a yard of mulch cover?
About 162 ft² at 2 in deep, 108 ft² at 3 in and 81 ft² at 4 in.
How deep should mulch be?
Two to three inches is enough for most beds, according to Mississippi State University Extension, and many guides say up to 3–4 in. Much deeper can keep water from reaching the soil.
How much mulch for a 10 × 10 bed?
At 3 in deep, 0.93 cubic yards or 13 bags of 2 ft³. At 2 in, 9 bags.
Bags or bulk?
Bags are easy to carry and store for a small bed. For a few cubic yards or more, ask a landscape yard for a bulk price delivered and compare it with the bag count on the ticket.
See also: Gravel calculator · Tons to yards
Sources
Bag size and bags per yard, depth 2–4 in: Gardening Know How, calculating soil and mulch coverage. Depth and topping up: Mississippi State University Extension. Mulch volcanoes: UConn Extension. Mulch weight: Inch Calculator, Aggregate Markets.