Mulch calculator: how much mulch do I need?
Measure the bed and pick a depth. You get cubic yards for a bulk delivery and the number of bags. Most beds need 2 to 3 inches of mulch.
- Cubic yards
- Bags from the label
- Soil and gravel too
For a round bed, multiply the radius by itself and by 3.14 to get square feet, then enter that as length with a width of 1.
Before you mulch
How it works
Cubic yards = area in square feet × depth in inches ÷ 324. A cubic yard is 27 cubic feet, so it covers 324 square feet at 1 inch deep.
Bags = cubic yards × 27 ÷ bag size, rounded up. Bags are often 2 cubic feet; change it to match yours.
Depth defaults to 3 inches. University of Illinois Extension recommends 2 to 3 inches of mulch after it settles. The same math works for topsoil or gravel at whatever depth you need.
About this tool
Who it's for
For anyone refreshing garden beds, or ordering soil or gravel by the yard.
Example
You enterA 20x5 bed at 3 inches
You getAbout 0.93 cubic yards, or 13 bags of 2 cubic feet.
What's different
- Gives both bulk yards and bag counts.
- Lets you set the bag size.
- Adds up several beds.
Gotchas and tips
- Fresh mulch settles, so a little extra depth is normal.
- More than 3 inches can keep water from reaching roots.
- Bulk delivery often has a minimum order.
Privacy: Runs entirely in your browser. Nothing you type is sent to us, and anything it remembers is saved on this device only.
Built and maintained by the GrabTheHammer team, using published figures from manufacturers and agencies, listed below. Updated November 2026. Spot a problem? Tell us.
Mulch questions
How much area does a yard of mulch cover?
One cubic yard covers 324 square feet at 1 inch deep, about 162 square feet at 2 inches or 108 square feet at 3 inches.
How deep should mulch be?
University of Illinois Extension recommends 2 to 3 inches after it settles. Keep it a few inches away from tree trunks and the house.
How many bags are in a yard?
A cubic yard is 27 cubic feet, so it takes 13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet.
Sources: Mississippi State Extension: yards to square feet; University of Illinois Extension: mulch depth.