Mulch Calculator

Mulch is estimated by area and depth, then ordered by the cubic yard: measure the bed, choose how deep to spread it and divide the volume by 27. Work out a rectangular or circular bed in cubic yards and cubic feet, plus how many bags of mulch you would need, the coverage in square feet and the bulk cost — with a waste allowance built in so you order enough to cover the ground.

%
$
Mulch needed — cubic yards
Cubic feet — ft³
Bags of mulch — at selected size
Coverage — sq ft
Estimated cost — bulk

How to Calculate Mulch

Pick the bed shape, measure, and read the yards.

1

Choose the bed shape

Use Rectangle for a square or rectangular bed, border or strip, and Circle for a round bed or a ring around a tree where you enter the diameter.

2

Enter the size and depth

Measure the bed in feet and the depth in inches — the two unit selectors handle the mix, so you never convert by hand. A 2 to 3 inch depth suits most beds. Set a quantity if you are mulching several identical beds.

3

Read yards, bags and cost

You get cubic yards and cubic feet, the number of bags for your bag size, the coverage in square feet, and — with a price per yard — the bulk cost. A waste allowance is added on top so you order enough.

Frequently Asked Questions

How much mulch do I need?
The amount of mulch you need is the area of the bed times how deep you want the layer. Measure the bed in feet, pick a depth in inches, and the calculator turns the depth into feet, multiplies by the area to get cubic feet, then divides by 27 to give cubic yards because bulk mulch is sold by the yard. For example a 20 by 10 foot bed at 3 inches deep is 200 × 0.25 = 50 cubic feet, which is about 1.85 cubic yards or roughly 25 bags of the 2 cubic foot size. Add a little extra on uneven ground so you are not caught short, and round up when you order.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so the number of bags depends on the bag size. The common bag holds 2 cubic feet, which means about 13.5 bags of that size make a cubic yard; the larger 3 cubic foot bag takes about 9 bags per yard. The calculator does the division for you: pick your bag size and it divides the total volume by the bag and rounds up to whole bags. Bagged mulch is easy to handle for a small bed, but once you need more than about two cubic yards it is usually cheaper and far less lifting to buy it loose by the yard and have it delivered.
How deep should mulch be?
For most garden beds a layer of 2 to 3 inches is right — deep enough to hold moisture, block weeds and moderate the soil temperature, without smothering the roots. Use nearer 3 inches for coarse bark or wood chips and on beds that dry out fast, and closer to 2 inches for fine or shredded mulch that packs down. Keep mulch a couple of inches clear of trunks and stems so they do not stay damp and rot. The depth field defaults to 3 inches; change it to see how the cubic yards and bag count move, since depth drives the volume just as much as the area does.
How much area does a yard of mulch cover?
Coverage depends entirely on the depth you spread it. One cubic yard is 27 cubic feet, so at 3 inches deep it covers about 108 square feet, at 2 inches about 162 square feet, and at 1 inch about 324 square feet — thinner layers stretch further. The calculator shows the coverage in square feet for the bed you entered, which is simply the plan area regardless of depth, so you can check it against the size of the space. Spring and autumn are the usual times to mulch, topping up the existing layer back to the depth you want rather than piling fresh mulch on year after year.
Is bulk mulch by the yard or bagged mulch cheaper?
For anything past a small bed, bulk mulch delivered by the cubic yard is almost always cheaper per yard than buying the same volume in bags. Bags make sense for a single planter, a narrow strip or a top-up, where a bulk delivery would carry a minimum load or drop fee that dwarfs the material. Once you need roughly two cubic yards or more, the per-yard price of loose mulch, even with delivery, usually beats hauling and opening dozens of bags. Use the price field to cost the bulk option by entering your local price per cubic yard, then compare that against the bag count the calculator shows for the same volume.

More home & DIY calculators