How much mulch do you need?
The amount of mulch you need depends on the area you want to cover and the depth of the layer. This calculator estimates the volume in cubic feet and cubic yards, along with the number of 2- or 3-cubic-foot bags required.
How to use the mulch calculator
- First, choose whether to enter the bed’s length and width or its total area.
- Next, enter the measurements and select the correct units.
- Then, enter the depth of the new mulch layer.
- After that, select the bag size that matches the product you may buy.
- Finally, add a 5% or 10% allowance(optional), then select Calculate mulch.
For an irregular garden bed, measure smaller sections separately and add their areas together before using the total-area option.
Mulch calculator formula
For measurements in feet, the area of a rectangular bed is:
Area = length × width
Convert the depth in inches to feet, then calculate the volume:
Cubic feet = area (sq ft) × depth (in) ÷ 12
Cubic yards = cubic feet ÷ 27
Number of bags = cubic feet ÷ bag volume, rounded up
If you select an extra allowance, the calculator applies that percentage to the volume before calculating the bag count. One cubic yard equals 27 cubic feet.
Example calculation
For a rectangular bed 20 feet long and 10 feet wide, with a 3-inch mulch layer:
- Area: 20 × 10 = 200 square feet
- Volume: 200 × 3 ÷ 12 = 50 cubic feet
- Cubic yards: 50 ÷ 27 ≈ 1.85 cubic yards
- 2-cubic-foot bags: 50 ÷ 2 = 25 bags
This example excludes any extra allowance. The calculator rounds bag counts up to a whole bag.
How deep should mulch be?
For many landscape beds, a layer around 2 to 3 inches is commonly used, but the appropriate depth depends on the material, the plants, and whether you are refreshing an existing layer. Avoid piling mulch against tree trunks or plant stems, and follow any guidance provided for the specific plants and mulch product.
Why might the amount differ from what I use?
The result is a volume estimate based on the dimensions and depth you enter. Actual use can vary because of uneven ground, irregular bed edges, material settling, spillage, and the volume stated on the bag. Check the product label and supplier’s units before ordering. The extra allowance is optional and is not included unless selected.
Frequently asked questions
How many square feet does one cubic yard of mulch cover?
Coverage depends on depth. One cubic yard covers 324 square feet at 1 inch deep, 162 square feet at 2 inches, 108 square feet at 3 inches, and 81 square feet at 4 inches.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet. That equals 13.5 bags of 2 cubic feet or 9 bags of 3 cubic feet by volume. Since you normally buy whole bags, the number needed for a specific job is rounded up by the calculator.
Can I enter metric measurements?
Yes. You can enter length and width in meters or centimeters, total area in square meters, and mulch depth in centimeters. The results are shown in cubic feet and cubic yards to match common bag and bulk-volume labels.
Does the calculator include extra mulch?
Not by default. Choose 5% or 10% under Extra allowance if you want to account for possible settling, spillage, or uneven areas. This is an optional planning allowance, not a guarantee of the exact amount needed.