MULCH CALCULATOR
How it works
A bed 20 ft × 10 ft, mulched 3 inches deep, using 2 ft³ bags.
- Convert the depth to feet: 3 in ÷ 12 = 0.25 ft.
- Volume: 20 × 10 × 0.25 = 50 ft³, which is 1.85 cubic yards.
- Bags: 50 ft³ ÷ 2 ft³ per bag = 25 bags exactly.
- A part bag cannot be bought, so any fraction rounds up.
25 bags of 2 ft³ mulch — or 1.85 cubic yards delivered in bulk.
Constants
| Constant | Value |
|---|---|
| Standard mulch bag | 2 ft³ |
| Large bag | 3 ft³ |
| Bark mulch density | 506 lb/yd³ |
| Cubic feet per cubic yard | 27 ft³ |
SOURCE — the standard US mulch bag is 2 ft³.
SOURCE — 3 ft³ bags are common for bark and larger nuggets.
SOURCE — bark mulch, dry: 506 lb/yd³ (woodchip ≈674, to ~800 wet).
SOURCE — 1 yd³ = 27 ft³, by definition.
Quick answers
A 20 ft × 10 ft bed at 3 inches deep takes 50 cubic feet of mulch: 25 standard 2 ft³ bags, or 1.85 cubic yards in bulk.
One cubic yard of mulch is 13.5 standard bags, so bulk delivery usually beats bags once you pass about ten bags.
Two inches of mulch refreshes an existing bed; three to four inches is a full application that will actually suppress weeds.
Bark mulch weighs only about 506 lb per cubic yard dry, which is why a yard of mulch is easy to move by wheelbarrow and a yard of gravel is not.
One cubic yard of mulch covers 108 square feet at 3 inches deep, or 162 square feet at 2 inches.
FAQ
How many bags of mulch are in a cubic yard?
13.5 bags at the standard 2 ft³ size, since a cubic yard is 27 cubic feet. That is 9 bags if you buy the 3 ft³ size, or 18 bags at 1.5 ft³.
How deep should mulch be?
Three inches is the usual target for a new bed and two inches to top up an existing one. More than four inches can hold water against stems and starve roots of air, so deeper is not better.
How much area does a bag of mulch cover?
A 2 ft³ bag covers 8 square feet at 3 inches deep, or 12 square feet at 2 inches. Divide the bag's cubic feet by the depth in feet to get the coverage.
Is bulk mulch cheaper than bags?
Usually, past about ten bags. A cubic yard equals 13.5 standard bags, and bulk is typically priced well under 13.5 bag prices — though you need somewhere for it to be dumped and a wheelbarrow to move it.
How much does a yard of mulch weigh?
About 506 lb dry for bark mulch, rising toward 800 lb when soaked. Woodchip runs heavier at roughly 674 lb per yard. A half-ton pickup can carry a yard of dry mulch but should not carry a yard of wet.
Should I add extra for settling?
Mulch settles noticeably in the first season, so many gardeners order the depth they want to see next spring rather than the depth they spread today. Adding 10% is a reasonable allowance.