Mulch is sold by volume, but garden beds are measured by area — that mismatch is why people come home with half what they need. Enter your bed size and depth below for cubic yards, bag counts and a bulk cost estimate.
How much mulch do you need?
Enter your garden bed size and mulch depth to get cubic yards for bulk delivery — or the number of bags to pick up.
Your estimate
Mulch settles and compacts after watering — the amount above is the standard estimate; add roughly 10% if the bed is freshly dug or the mulch is very coarse. One cubic yard covers about 108 sq ft at 3 inches deep.
How to use this mulch calculator
- Measure the length and width of each bed (split odd shapes into rectangles).
- Choose a depth — 3 inches is standard for flower beds, 2 inches for a top-up over existing mulch, 4 inches for new beds and weed suppression.
- Decide bags vs bulk: under about 1 cubic yard, bags are simpler; over that, bulk delivery is far cheaper per cubic foot.
How we calculate mulch
Volume = length × width × depth. Cubic yards = cubic feet ÷ 27. Bags = cubic feet ÷ 2 (the standard bag size), rounded up. One cubic yard covers about 108 sq ft at 3 inches deep, 162 sq ft at 2 inches, and 81 sq ft at 4 inches.
Mulch calculator FAQs
How much mulch do I need for a 100 sq ft bed?
At the standard 3-inch depth, a 100 sq ft bed needs 25 cubic feet of mulch — about 0.93 cubic yards, or roughly 13 standard 2 cu ft bags. The calculator above gives the exact figure for your bed and depth.
How deep should mulch be?
Two to four inches. Three inches is the standard for flower beds: enough to block weeds and hold moisture without suffocating roots. Keep mulch a few inches away from tree trunks and plant stems — piling it against bark invites rot.
Is it cheaper to buy mulch in bags or bulk?
Under about 1 cubic yard, bags are simpler and often cheaper once delivery fees count. Above that, bulk wins clearly — a cubic yard bought in bags can cost two to three times the bulk price.
How much area does a cubic yard of mulch cover?
One cubic yard (27 cubic feet) covers about 162 sq ft at 2 inches deep, 108 sq ft at 3 inches, and 81 sq ft at 4 inches.