How this is worked out
Length times width times depth gives the volume, with each length rounded to the nearest sixteenth first and depth turned from inches into feet. A round bed is pi times the diameter squared over four, with pi as 355/113, the value Handyman Calc uses for every circle. Then 5% goes on for settling, or what you type.
Bulk mulch is sold by the cubic yard, which is 27 cubic feet. Bagged mulch usually comes in 2 cu ft bags, and the calculator rounds bags up. Gravel, sand and topsoil are in the material list too, with their usual bag sizes.
For common beds already worked out, there's a mulch chart for 2 and 3 inch depths, with a PDF to print.
On your phone, on the job site
Handyman Calc, our free app, has this landscape screen for mulch, gravel, sand and topsoil and fourteen more calculators. It works with no signal, and it's free.
▶ Try it in your browser Download on the App Store ▶ Get it on Google Play
Charts worked out with the same math:
- how many bags of concrete a slab takes
- how many sheets of drywall a room takes
- a fraction to decimal chart for inches
- how much paint a room takes
- how much mulch a bed takes
- a roof pitch chart
- how many steps a rise takes
- the diagonal that squares a frame
- board feet for common lumber
More calculators:
Frequently asked questions
How much mulch do I need for 200 square feet?
1.94 cubic yards at 3 inches deep, with 5% extra for settling. In 2 cu ft bags that's 27. At 2 inches deep it's two thirds of that.
How much mulch for 100, 300 or 500 square feet?
At 3 inches deep with 5% for settling: 0.97 cubic yards (14 bags) for 100 sq ft, 2.92 yards (40 bags) for 300, and 4.86 yards (66 bags) for 500.
How do you calculate mulch?
Multiply the bed's length and width in feet, then by the depth in inches divided by 12. That's cubic feet. Divide by 27 for cubic yards, or by 2 for 2 cu ft bags. Add about 5% for settling.
How deep should mulch be?
Two to three inches in most beds. Deeper than about four inches can keep water and air from the roots, and less than two lets weeds through.
How many bags of mulch are in a yard?
13.5 bags of 2 cu ft, since a cubic yard is 27 cubic feet. Buy 14. With 3 cu ft bags it's 9.