How to use this calculator
- Choose rectangle for beds and borders or circle for tree rings and round beds.
- Enter the dimensions in feet and the depth in inches. Two to three inches is typical for beds.
- Pick the bag size printed on the mulch bags at your store.
- Add a price per cubic yard to compare the cost of bulk delivery.
How the numbers are calculated
The calculator multiplies the area by the depth in feet to get cubic feet, adds your waste allowance, and divides by 27 to get cubic yards. For bags it divides the cubic feet by the volume of one bag and rounds up.
A 2 cubic foot bag is about one-thirteenth of a cubic yard, so a full yard is roughly 13.5 bags. A 3 cubic foot bag works out to 9 bags per yard.
Worked example
A bed 25 ft long and 4 ft wide has an area of 100 sq ft. At 3 in deep that is 100 × 0.25 = 25 cubic feet. With 5% extra you need 26.25 cubic feet, which is 0.97 cubic yards, or 14 bags of 2 cubic feet.
Tips before you buy
- Two to three inches of mulch is enough for most beds. Thicker layers can hold too much moisture against plant stems.
- Keep mulch a few inches away from tree trunks and plant stems rather than piling it against them.
- Mulch breaks down and settles, so plan to top it up each year by about an inch instead of starting over.
- Buying in bulk is usually cheaper than bags once you need about a cubic yard or more, but check delivery fees.
- Pull weeds first, then lay mulch. A layer of cardboard or fabric underneath helps suppress new weeds.
Frequently asked questions
How much area does one cubic yard of mulch cover?
One cubic yard covers about 162 square feet at 2 inches deep, 108 square feet at 3 inches, and 81 square feet at 4 inches.
How many bags of mulch are in a cubic yard?
About 13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet. Bag sizes vary by brand, so read the label.
How deep should mulch be?
Two to three inches is the usual range for garden beds. Use the lower end for fine mulch and the upper end for coarse bark.
Should I add extra mulch for settling?
A small allowance of about 5% covers uneven ground and spillage. The calculator adds it for you.
Related calculators
These results are estimates for planning purposes. Material sizes, densities and local requirements vary, so confirm quantities with your supplier or a qualified contractor before ordering.
Last updated October 11, 2026.