Mulch Calculator
Mulch is sold by the cubic yard in bulk and by the bag at the store. Measure your bed, pick a depth, and this works out how much you need both ways.
Cubic yards
0.93cu yd
- Bags (2 cu ft)
- 13 bags
- Cubic feet
- 25 cu ft
How it’s calculated
Volume = bed area × depth. Area is length × width in feet; multiply by the depth in feet (inches ÷ 12) for cubic feet, then divide by 27 for cubic yards. Bags = cubic feet ÷ the bag's size, rounded up to whole bags.
Worked example
A 10 ft × 20 ft bed at 3 inches deep: area = 200 sq ft; volume = 200 × (3 ÷ 12) = 50 cubic feet = 50 ÷ 27 ≈ 1.85 cubic yards. In 2-cubic-foot bags that's 50 ÷ 2 = 25 bags.
FAQs
- How deep should mulch be?
- 2–4 inches is the sweet spot for organic mulch: 2–3 inches to refresh an existing bed, 3–4 inches for a bare one. Going deeper doesn't just waste mulch — too-deep organic mulch traps moisture against roots (rot), harbors pests, and can turn hydrophobic and shed water instead of soaking in.
- Should mulch touch tree trunks or plant stems?
- No — keep it a few inches clear of trunks and stems. Mulch heaped against bark (a “mulch volcano”) traps moisture and invites rot, girdling roots, and disease, even though you see it done everywhere.
- How much does a cubic yard of mulch cover?
- About 324 square feet at 1 inch deep, 162 sq ft at 2 inches, or roughly 108 sq ft at 3 inches — depth and coverage trade off directly.
- Should I round up when buying mulch?
- Yes. The bag count here already rounds up to whole bags; for bulk, add about 5–10% for uneven ground and settling, and note that suppliers often sell by the whole or half cubic yard. Better a little extra than coming up short mid-bed.
Sources
- Coverage geometry: 1 cubic yard (27 cu ft) spread 1 inch deep covers 324 sq ft. Bagged mulch volume varies by product (commonly ~2 cu ft for wood mulch) and is printed on the bag.