How to Estimate the Amount of Mulch Needed

Measuring the Area

• 1

  Measure the length and width (in feet) of a square or rectangle to be mulched. Multiply the length times the width. The result is the area in square feet.

• 2

  Measure across the widest part of a circle to be mulched and divide the measurement by two. Multiply this number by itself. For example, if the circle is 8 feet across, dividing by 2 gives you 4 feet. Four times 4 is 16. Then multiply the result (16) by 3.14 (the number called pi). This gives you the area of the circle in square feet.

• 3

  Measure the height of a triangle with equal sides to be mulched. Multiple by the length of the base, then divide by two. This is the area of the triangle in square feet.

• 4

  Divide an irregularly shaped area into measurable units (squares, rectangles, circles and triangles) until you have accounted for all the areas to be mulched. Add the areas (in square feet) to get the total square feet. (The result won't be as accurate, but you can still come close to the correct amount.)

Estimating the Amount of Mulch

• 5

  Decide what type of mulch you will use, and how deep the mulch should be. Some mulches like cocoa hulls should be applied at a depth of only 1 inch, while others like wood chips should be applied to a depth of 2 to 4 inches.

• 6

  Multiply your total square feet of area by the depth in inches that you want the mulch to be, and divide by 324 square feet, which is 1 cubic yard 1 inch deep. The result is the number of cubic yards you will need.

• 7

  Buy this amount of bulk mulch. If you are buying bagged mulch, make one more calculation. One cubic yard equals 27 cubic feet, so multiply the total cubic yards from the previous step by 27 to get the number of cubic feet you will need. Purchase the number of bags to come as close as you can to what you will need.