Mulch Calculator
Calculate Mulch for a Rectangle
Calculator Use
Calculate how much mulch or other landscaping material you need. Select the shape of your mulch bed and input the dimensions in feet, inches, meters or centimeters.
The mulch calculator provides the answer in cubic yards, cubic feet, and cubic meters for the volume of mulch required to fill your space. Also calculate the cost of mulch or other material when you enter the price for bulk mulch by the cubic yard or cubic meter. If you're buying mulch by the bag, enter the price per bag and select how much mulch is in each bag.
How to Calculate Mulch Volume
The method you use to calculate how much mulch you need depends on the shape of the area you want to cover with mulch. You can see the methods to calculate mulch in landscaping beds of different shapes below. For this example we'll calculate how much mulch you need for a landscaping bed with a rectangle shape.
Anytime you fill an area with material of a certain depth you want to calculate the volume of the material. First multiply the length and width dimensions of your space to get the area in square feet. Then multiply the area by the depth of the material in the same units (feet in this case) to get the volume in cubic feet. If you need to convert this to cubic yards, divide cubic feet by 27.
Example: How Much Mulch Do I Need?
Say you have 5 ornamental landscaping beds around your house. They are rectangular in shape and about the same size, measuring 10' 6" long by 3' wide. You want to cover the beds to have a layer of mulch that is 3" deep. You'll need to calculate how much mulch you need for one bed, and then multiply that by 5 to cover each of your beds.
To calculate mulch for one bed multiply the length times the width, and then multiply that by the depth. Keep in mind that the units must be the same on each of these measurements. We'll use feet here, and a partial foot will be a decimal number.
- First convert 10 feet 6 inches into a decimal. 6 inches divided by 12 inches per foot is 0.5, so your bed is 10.5 feet long.
- Multiply length times width. 10.5 ft × 3 ft = 31.5 square feet
- Convert your depth of 3" into decimal feet. 3 inches divided by 12 inches per foot is 0.25.
- Multiply your square footage by your depth. 31.5 sq ft × 0.25 ft = 7.875 cubic feet.
- You need mulch for 5 beds, so 5 × 7.875 = 39.375 cubic feet.
- Divide by 27 to convert the mulch volume into cubic yards. 39.375 ÷ 27 = 1.458 cubic yards
The Mulch Calculator makes this calculation easy by doing all the conversions and the math for you. You can also input how much your mulch will cost by the unit, like per cubic yard or cubic meter, or by the bag. The calculator finds the cost of your quantity of mulch given the cost per unit.
If you are buying your mulch by the bag, input length, width and mulch depth and select the size of the bag you'll purchase. The mulch calculator will tell you how many bags you need and how much it will cost if you input price per bag.
Note: If you already have the square footage of an area and want to calculate cubic yards you can still use this calculator. Select a rectangle shape and enter your square feet as the length, and enter 1 as the width. Then enter how deep you want the mulch and click the Calculate button. Your answer will appear in cubic yards.
Mulch Volume Formulas and Area Calculations
Square Area
Calculate mulch volume using depth for a square area
Using measurements in feet:
Area ft2 = 2 × Side Length
Volume ft3 = Depth × Area
Volume in Cubic Yards yd3 = Volume ft3 / 27
Rectangle Area
Calculate mulch volume using depth for a rectangle area
Using measurements in feet:
Area ft2 = Length × Width
Volume ft3 = Depth × Area
Volume in Cubic Yards yd3 = Volume ft3 / 27
Rectangle Border Area
Calculate mulch volume using depth for a rectangle border area
Using measurements in feet:
Inner Area (ft2) = Length × Width
Total Area (ft2) = (Length + (2 × Border Width)) × (Width + (2 × Border Width))
Area (ft2) = Total Area - Inner Area
Volume (ft3) = Depth × Area
Volume in Cubic Yards (yd3) = Volume (ft3) / 27
Circle Area
Calculate mulch volume using depth for a circle area
Using measurements in feet:
Area (ft2) = Pi × (Diameter/2)2
Volume (ft3) = Depth × Area
Volume in Cubic Yards (yd3) = Volume (ft3) / 27
Pi = 3.14
Circle Border Area
Calculate mulch volume using depth for a circle border area
Using measurements in feet:
Outer Diameter = Inner Diameter + (2 × Border Width)
Outer Area (ft2)
= Pi × (Outer Diameter/2)2
Inner Area (ft2)
= Pi × (Inner Diameter/2)2
Area (ft2) = Outer Area - Inner Area
Volume (ft3) = Depth × Area
Volume in Cubic Yards (yd3) = Volume (ft3) / 27
Pi = 3.14
The Circle Border and Annulus below are the same shape, just measured differently.
Annulus Area
Calculate mulch volume using depth for a annulus area
Using measurements in feet:
Outer Area (ft2)
= Pi × (Outer Diameter/2)2
Inner Area (ft2)
= Pi × (Inner Diameter/2)2
Area (ft2) = Outer Area - Inner Area
Volume (ft3) = Depth × Area
Volume in Cubic Yards (yd3) = Volume (ft3) / 27
Pi = 3.14
The Circle Border and Annulus above are the same, just measured differently.
Triangle Area
Calculate mulch volume using depth for a triangle area
Using measurements in feet:
Area (ft2) = (1/4) × square root[ (a+b+c) × (b+c-a) × (c+a-b) × (a+b-c) ]
Volume (ft3) = Depth × Area
Volume in Cubic Yards (yd3) = Volume (ft3) / 27
Trapezoid Area
Calculate mulch volume using depth for a trapezoid area
Using measurements in feet:
Area (ft2) = ((a + b) / 2 )h
Volume (ft3) = Depth × Area
Volume in Cubic Yards (yd3) = Volume (ft3) / 27