Mulch Calculator
Yards and bags for beds and borders — with the depth guide on the page, because “how much mulch” is really “how deep, over how much bed.”
Bag count uses the standard 2 cu ft bag. Depth guide: 2 in for a refresh over old mulch, 3 in for new beds, 4 in where weeds are the whole problem. One cubic yard covers 108 sq ft at 3 inches.
How the math works
Length × width × depth = cubic feet, ÷ 27 = cubic yards. Bags are the standard 2 cu ft bag — the size every home center sells — so bags = cubic feet ÷ 2. The coverage numbers worth memorizing: a cubic yard covers 324 sq ft at 1 inch, 162 at 2 inches, 108 at 3 inches, 81 at 4 inches.
Depth is the whole game. Two inches refreshes the look over existing mulch. Three inches is the working depth for new beds — enough to hold moisture and slow weeds. Four inches is for weed-suppression over bare, ugly ground. Past that you are burying plant crowns and wasting money, and fresh mulch settles about 10% in the first month, which is what the waste factor is doing here.
A worked example
A 20 ft × 10 ft bed at 3 inches: 200 sq ft × 0.25 ft = 50 cubic feet = 1.85 yards exact, 2.04 yards with the 10% settling factor — or 28 of the 2 cu ft bags. Two yards bulk, delivered, is one phone call; 28 bags is a Saturday. Run your beds above, one at a time or added together.
Questions from the field
How many bags of mulch equal a yard? 13.5 — call it 14 bags of the standard 2 cu ft size per cubic yard. (A yard is 27 cu ft; 27 ÷ 2 = 13.5.)
How much mulch do I need for 1,000 sq ft of beds? At 3 inches: 1,000 ÷ 108 ≈ 9.3 yards, about 10 with settling. At 2 inches for a refresh: about 6.2 yards.
How deep should mulch be? 3 inches for most beds, 2 for a refresh, 4 for weed duty — and keep it a few inches off trunks and stems. Mulch volcanoes against a tree trunk rot the bark you were trying to protect.
Bulk or bags? Under a yard, bags are fine and cleaner. Over 2 yards, bulk delivered almost always wins on price and trips. Between the two, the calculator gives you both numbers so the comparison is honest.
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