Mulch Calculator — How Much Mulch Do You Need?
A 10×10 ft bed (100 sq ft) at 3 inches deep needs about 0.93 cubic yards of mulch — roughly 13 bags of 2 cubic feet. One cubic yard of mulch covers about 108 square feet at 3 inches deep, and equals 13.5 standard 2 cu ft bags.
Enter the length and width of your bed and how deep you want the mulch. This calculator instantly tells you the volume in cubic yards and cubic feet, plus how many bags to buy based on the bag size you choose.
How to use this calculator
- Measure the length and width of your bed in feet. For odd shapes, split the area into rectangles and add them up.
- Choose a depth: 2–3 inches is standard for flower beds, 3–4 inches helps suppress weeds.
- Pick the bag size sold at your store (most bagged mulch is 2 cubic feet).
- Read off the cubic yards if buying in bulk, or the bag count if buying bagged.
The formula
Mulch is sold by volume, so the math starts with the volume of your bed.
Volume (cubic feet) = length (ft) × width (ft) × depth (in) ÷ 12. We divide by 12 to convert the depth from inches to feet.
Cubic yards = cubic feet ÷ 27, because there are 27 cubic feet in a cubic yard. Bulk mulch is usually priced per cubic yard.
Bags = cubic feet ÷ bag size, rounded up. A standard bag holds 2 cubic feet, so one cubic yard ≈ 13.5 bags.
Worked example
A 10 ft × 12 ft bed at 3 inches deep, buying 2 cu ft bags.
Area = 10 × 12 = 120 sq ftDepth in feet = 3 ÷ 12 = 0.25 ftVolume = 120 × 0.25 = 30 cubic feetCubic yards = 30 ÷ 27 ≈ 1.11 cubic yardsBags = 30 ÷ 2 = 15 bags
You need about 1.11 cubic yards of mulch — that is 15 bags of 2 cu ft each.
Reference tables
| Depth | Coverage per cubic yard | 2 cu ft bags per cubic yard |
|---|---|---|
| 1 in | 324 sq ft | 13.5 |
| 2 in | 162 sq ft | 13.5 |
| 3 in | 108 sq ft | 13.5 |
| 4 in | 81 sq ft | 13.5 |
Frequently asked questions
How much mulch do I need for a 10x10 area?
A 10 ft × 10 ft area (100 sq ft) at 3 inches deep needs 25 cubic feet, which is about 0.93 cubic yards or roughly 13 bags of 2 cubic foot mulch.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet. With standard 2 cubic foot bags that is 13.5 bags, so plan on 14 bags to cover one cubic yard.
How deep should mulch be?
For most flower beds 2–3 inches is enough. To suppress weeds and retain moisture, go 3–4 inches. Avoid piling mulch against plant stems or tree trunks.
How much area does a cubic yard of mulch cover?
One cubic yard of mulch covers about 100 square feet at 3 inches deep, 160 square feet at 2 inches deep, or 80 square feet at 4 inches deep.