How the mulch calculator works
The formula
Mulch is sold by volume: cubic feet = area (sq ft) × depth (inches) ÷ 12, and bulk mulch sells by the cubic yard (1 yard = 27 cu ft). Bagged mulch is typically 2 cu ft (occasionally 1.5 or 3 — check the bag), so bags = total cu ft ÷ 2.
Depth is the decision that matters
- 2 inches: refreshing beds that still have a working layer — the annual top-up.
- 3 inches: the standard. Suppresses most weeds and holds moisture without smothering roots.
- 4 inches: new beds or serious weed pressure. More than this starts blocking water and air exchange.
Beyond 4 inches you're not mulching, you're burying — roots grow up into the pile and the "mulch volcano" against tree trunks invites rot and rodents. Keep mulch a hand-width clear of trunks and stems.
Bulk vs bags
Roughly: under 1 cubic yard, bags win on convenience; over ~2 yards, bulk delivery usually wins on price per yard and your back. Between, it's a wash — price both. Our result shows the bag count and yardage side by side so you can price your local options honestly.