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Mulch Calculator: How Much Mulch Do I Need?
Enter your bed dimensions and the depth you want. The calculator gives cubic yards for bulk delivery and bag counts for 2 and 3 cubic foot bags, because the most common mulch mistake is buying bags for a job that should have been one bulk delivery, or the reverse.
How This Calculator Works
Volume is area (length times width) times depth in feet. Divide cubic feet by 27 for cubic yards. Bagged mulch is sold by the cubic foot, most commonly 2 cubic foot bags, so the bag count is cubic feet divided by bag size, rounded up. Depth is the whole game: doubling depth doubles the order.
Worked Example
A 20 by 4 foot bed is 80 square feet. At 3 inches deep that is 20 cubic feet, which is 0.74 cubic yards, or 10 bags of 2 cubic feet. At 4 inches it becomes 27 cubic feet, a full cubic yard, so depth choice changes the order size more than bed size estimates do.
Coverage of 1 cubic yard of mulch, by depth
| Item | Figure |
|---|---|
| 2 inches deep | 162 sq ft |
| 3 inches deep | 108 sq ft |
| 4 inches deep | 81 sq ft |
| 6 inches deep | 54 sq ft |
Frequently Asked Questions
How deep should mulch be?
3 inches is the working standard for beds: enough to suppress weeds and hold moisture. Go 2 inches to refresh an existing layer, 4 inches for a new bed over bare soil. Keep mulch a few inches away from trunks and stems.
Is bulk or bagged mulch cheaper?
Bulk wins on price per cubic foot almost always, and one cubic yard equals about 14 bags of 2 cubic feet. Bags win on handling for small beds, slopes and anywhere a wheelbarrow cannot go.
How many bags of mulch make a cubic yard?
About 14 bags at 2 cubic feet each (13.5 exact), or 9 bags at 3 cubic feet each.
How do I measure an irregular bed?
Break it into rough rectangles, calculate each, and add them. Or pace the total square footage and use area times depth: the calculator maths is identical.