Mulch Calculator
Find out how much mulch your beds need, in cubic yards for a bulk delivery or in bags if you are buying from a garden centre.
Enter the bed dimensions and depth and the calculator gives volume, bag count, approximate weight and an optional cost.
Handles rectangular, circular and triangular beds, or you can enter a known area.
How to use the mulch calculator
Enter your bed dimensions or known area.
Set the depth — 2 to 3 inches is usual.
Read cubic yards and bag counts.
Why use the Build Tally mulch calculator
Bags and bulk
See both, including 50 L metric bags.
Any bed shape
Rectangles, circles, triangles, or enter an area.
Weight estimate
Useful for judging what your vehicle can carry.
Free and private
Nothing uploaded, no account.
How deep to spread mulch
Two to three inches is right for most beds. That is enough to suppress weeds and hold moisture, without the problems that come with going deeper — mulch piled thickly holds water against stems and can starve roots of oxygen. Keep mulch pulled back a few inches from tree trunks and plant stems; the volcano of mulch heaped against a trunk is a genuinely common way to kill a young tree.
Bags or bulk
One cubic yard equals 13.5 of the 2 cubic foot bags, or 9 of the 3 cubic foot bags. Bulk is almost always cheaper per yard once you are ordering two yards or more, and it saves a great deal of plastic. Below about a yard, bags win on convenience — and they are far easier if you have to carry material through a house or gate.
How far a yard goes
At the recommended 3 inch depth, one cubic yard covers about 108 square feet. At 2 inches it covers 162 square feet. Mulch is light — around 400–800 lb per cubic yard depending on type and moisture — so a pickup can usually take two to three yards, unlike soil or gravel.
Read the guide: How Much Mulch Do I Need? Bags, Cubic Yards and the Right Depth
Frequently asked questions
How much mulch do I need?
Multiply bed area in square feet by depth in feet and divide by 27. At 3 inches deep, one cubic yard covers about 108 square feet.
How many bags of mulch in a cubic yard?
13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet.
How deep should mulch be?
Two to three inches. Deeper can suffocate roots and hold moisture against stems.
How much does a cubic yard of mulch weigh?
Usually 400–800 lb depending on the material and how wet it is — far lighter than soil or gravel.
How much area does a bag of mulch cover?
A 2 cubic foot bag covers about 8 square feet at 3 inches deep, or 12 square feet at 2 inches.
Should I remove old mulch first?
Not usually. Rake and loosen the old layer and top up to the target depth rather than adding a full new layer each year.
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