Coverage Calculator: 

http://1800mulchpro.com/mulch-calculator.html

BULK MATERIALS FORMULA:

Length x Width x (multiplier) = Cubic Feet

Since there are 27 cubic feet in a cubic yard you then divide by 27.

Example: If you would like to find out how much mulch you need to cover a 10' x 10' area 4 inches thick:

10 x 10 x .33 (from multiplier table below)  = 33 cu. ft

33 cu. ft. divided by 27 = 1.2 yards.

 

Depth in inches	Multiplier
1 inch	.08
2 inches	.16
3 inches	.25
4 inches	.33
5 inches	.43
6 inches	.5
7 inches	.58
8 inches	.66
9 inches	.75
10 inches	.83
11	.91
12 inches	1

For mulch we use the general formula:

Length X Width x .3 divided by 27 = Cubic Yards