Mulch Calculator

Enter the size of your bed and the depth you want to see how much mulch to buy, in bulk or in bags.

Quick answer

1.94 cubic yards — 27 bags of 2 ft³

Includes 5% waste.

Buy list

Mulch
27 × 2 ft³ bag
26.25 bags exact
Price per 2 ft³ bag ($)

Add your local prices to see a total.

Project figures

Volume before waste: 1.85 cubic yards
Volume to buy: 1.94 cubic yards
1.5 ft³ bags: 35 (35 exact)
2 ft³ bags: 27 (26.25 exact)
3 ft³ bags: 18 (17.5 exact)

Diagram

Not to scale where a dimension is very thin or long.

Show the math

Volume = bed area × depth = 50 ft³ (1.85 cubic yards).
Add 5% waste: 50 ft³ × 1.05 = 52.5 ft³.
52.5 ft³ ÷ 2 ft³ per bag = 26.25 bags, rounded up to 27.

Assumptions and notes

Bag sizes are the loose volume printed on the bag.
Quantities and cost only. For structural, load or code questions, check your local building code and a qualified professional.

How it works

This calculator works out how much mulch covers a garden bed to the depth you want, in cubic yards for a bulk delivery or in bags for a trip to the garden centre. It can also size the landscape fabric that goes underneath, so the whole job ends up on one list.

The formula

Mulch fills a thin, flat layer, so the volume is the bed area times the depth. You can give the bed as a length and a width, or type the total area if you have already measured it, which is handy for curved or odd-shaped beds. The depth is usually given in inches and the bed in feet; the calculator converts everything to the same unit before multiplying, then reports the result in cubic yards (or cubic metres in metric).

A worked example

The page opens with a bed 20 ft long and 10 ft wide, covered 3 in deep. The area is 200 square feet and 3 in is a quarter of a foot, so the bed holds 200 × 0.25 = 50 cubic feet. With 5% added for settling and spill, that becomes 52.5 cubic feet, or 1.94 cubic yards. In 2 cubic foot bags that is 26.25 bags, so you buy 27. In 1.5 cubic foot bags it is exactly 35 bags: the calculator recognises an exact fit and does not add a 36th bag because of a rounding quirk.

Waste and bag sizes

Fresh mulch is fluffy and settles after the first rain, and some always ends up on the lawn or the path. The default allowance of 5% covers that for most beds; you can change it if your edges are very neat or very ragged. Bags are sold by loose volume, commonly 1.5 ft³ bag, 2 ft³ bag, 3 ft³ bag. The buy list uses the size you pick, and the project figures show the count for every size so you can see which works out simplest. Bulk suppliers sell by the cubic yard, which is the first number in the quick answer.

Landscape fabric

Fabric under mulch is optional. When you switch it on, the calculator gives the area to cover, which is simply the bed area with no waste added. If you type the area of one roll as printed on the label, it also counts the rolls to buy. Rolls are joined with an overlap, so buy a little extra if the bed needs several strips side by side.

Measuring tips

For a curved bed, split it into rectangles and add their areas, then use area mode.
Measure the depth you want after settling; most beds look finished at 2 to 3 inches.
Subtract large stepping stones or patios that will not be covered.

Common mistakes

Entering the depth in feet: 3 ft of mulch is twelve times more than 3 in.
Forgetting the mulch already in the bed when you are only topping it up.
Comparing bag prices without comparing bag sizes; use the price fields to check.