How to Calculate Wood Chip Mulch

Updated July 19, 2017

Mulching is one of the most important things you can do for your garden beds. It helps the soil hold moisture, keeps weeds from emerging and prevents soil-borne diseases from splashing onto leaves during heavy rains. Wood mulch also adds to the beauty of the landscape. Mulch is usually sold by the square yard. Take the time to calculate how many square yards you need to save yourself time and money.

Measure the length and width of a square or rectangular bed in feet. Multiply the length times the width to get the number of square feet in your bed.

Measure round beds from the centre of the bed to the outer edge in feet. Multiply this measurement by itself. For example, if the measurement is 5 feet, multiply 5 by 5 to get 25. Multiply the result (25 in the example) by 3.14. The result is the number of square feet of your round bed.

Calculate the number of cubic feet you need based on the desired depth of the mulch. Wood chip mulch is usually applied at a depth of 2 to 3 inches. Divide the depth by 12. For example, if you plan to apply the mulch 3 inches deep divide 3 by 12 for a result of 0.25. Multiply this result by the number of square feet in your bed. The result is the number of cubic feet of mulch required.

Divide the cubic feet by 2 to determine the number of 2-cubic-foot bags you need. Mulch is usually sold in 2-cubic-foot bags in garden and discount stores.

Divide the cubic feet by 27 to convert it to cubic yards. Mulch sold in bulk is usually measured in cubic yards.


Save money by ordering mulch in bulk if your calculations show that you need a cubic yard or more.

Things You'll Need

  • Tape measure
  • Calculator (optional)
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About the Author

Jackie Carroll has been a freelance writer since 1995. Her home-and-garden and nature articles have appeared in "Birds & Blooms" and "Alamance Today." She holds a Bachelor of Science in medical technology from the University of North Carolina.