Mulch Calculator

Calculate Mulch for a Circle Border

Figure out how much mulch or other landscaping material you need. Choose the shape of your mulch bed then enter dimensions. You can use feet, inches, meters or centimeters.

The mulch calculator shows the volume in cubic yards, cubic feet and cubic meters. You can also calculate the cost. Enter the bulk price by the cubic foot, cubic yard or cubic meter. If you're buying mulch by the bag, enter the price per bag and how much mulch each bag holds.

What is Mulch and Why Use It?

Mulch is a protective layer of material spread on top of soil, usually around plants. It can be made of wood chips, shredded leaves, straw, grass clippings, stones or rubber. Using the right mulch can help your yard, landscape project or garden, depending on the type of mulch you choose. Mulch can:

• Block weed growth
• Add nutrients to the soil as it breaks down
• Protect roots from changes in temperature
• Keep soil structure intact
• Retain moisture
• Improve the look of your garden or landscape project

Why the Right Amount of Mulch Matters

Using too little mulch can lead to an increase in weeds, drier soil, variable soil temperature and increased erosion and runoff. Bare soil can also harm helpful microbes that ensure healthy topsoil over time.

Using too much mulch can also cause problems for plants. If your mulch layer is too thick it can prevent oxygen from reaching the roots and harm them during dry spells. Mulch around trees can rot tree bark and spread disease by holding moisture against trunks. And too much mulch can even delay plant dormancy which is a problem as the months get cooler.

This mulch calculator simplifies the process of figuring out how much mulch to use. You can accurately estimate the amount of mulch needed for your landscape or garden project and avoid under- or over-applying mulch.

How to Apply Mulch Correctly

• Use 2–3 inch layer for fine mulch
• Use a 3–4 inch layer for coarser mulch
• Around large plants or trees, leave a 3 inch gap between the mulch and the trunk, making a doughnut shape—not a volcano
• Check the depth over time so mulch doesn't build up, especially near tree trunks

Types of Mulch: Organic vs. Inorganic

Mulch comes in two main varieties: organic and inorganic.

• Organic mulch (bark, wood chips, straw) breaks down and feeds the soil. It works well in flower beds and vegetable gardens.
• Inorganic mulch (rubber, stone) does not break down. It lasts longer and needs less care. It's best for pathways and play areas.

Use these guides to find the right mulch for your landscape conditions and applications.

Coverage math: 1 cu ft covers ~6 sq ft at 2" (since 2" = 1/6 ft) and ~4 sq ft at 3" (3" = 1/4 ft). Add 5–10% extra for waste and settling.

How to Calculate Mulch Volume

The method you use to figure out how much mulch you need depends on the shape of the area you want to cover with mulch. You can see how to calculate mulch in landscaping beds of different shapes below. In this example, we calculate how much mulch you need for a rectangle landscaping bed.

When you fill an area to a certain depth, you need the volume of the material.

1. Multiply length × width to get the area in square feet
2. Multiply the area × the depth (use the same units—feet here) to get cubic feet. This is the volume of mulch you need.
3. To change cubic feet to cubic yards, divide by 27

Example: How Much Mulch Do I Need?

You have 5 ornamental landscaping beds. They are rectangular in shape and about the same size, measuring 10' 6" long by 3' wide. You want to cover the beds with a layer of mulch that is 3" deep. To get the amount for all five beds, first calculate how much mulch you need for one bed, and then multiply that by 5.

To find the volume of mulch you need for one bed, first multiply the length times the width to get the area. Then multiply that number by the depth. The units must be the same on each of these measurements. We use feet here, and a partial foot will be a decimal number.

1. Convert 10'6" into feet as a decimal number: 6" ÷ 12 = 0.5 ft, so your bed is 10.5 feet long
2. Find the area, by multiplying length times width: 10.5 ft × 3 ft = 31.5 square feet (ft²)
3. Convert the depth of 3" into decimal feet: 3" ÷ 12 = 0.25 ft
4. To find the volume for one bed, multiply square footage by your depth: 31.5 ft² × 0.25 ft = 7.875 cubic feet (ft³)
5. For 5 beds: 5 × 7.875 ft³ = 39.375 ft³
6. Convert cubic feet to cubic yards: 39.375 ÷ 27 = 1.458 cubic yards (y³)

The Mulch Calculator makes this easy. It does the math and the changes the units for you. You can also enter the cost by the unit, like per cubic yard or cubic meter, or by the bag.

• For bulk mulch, type the price per cubic yard or cubic meter
• For bagged mulch, enter the dimensions, the price per bag and pick the bag size; the calculator tells you how many bags you need and the total cost

Note: If you already know the square footage and want cubic yards for your rectangle shape, enter your square feet as the length, enter 1 as the width, set the mulch depth and click Calculate. Your answer will appear in cubic yards.

Mulch Volume Formulas and Area Calculations

Square Shape

Calculate mulch volume using depth for a square

Using measurements in feet:

Area ft² = 2 × Side Length

Volume ft³ = Depth × Area

Volume in Cubic Yards yd³ = Volume ft³ ÷ 27

Rectangle Shape

Calculate mulch volume using depth for a rectangle

Using measurements in feet:

Area ft² = Length × Width

Volume ft³ = Depth × Area

Volume in Cubic Yards yd³ = Volume ft³ ÷ 27

Rectangle Border Shape

Calculate mulch volume using depth for a rectangle border

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 Shape

Calculate mulch volume using depth for a circle

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 Shape

Calculate mulch volume using depth for a circle border

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 Shape

Calculate mulch volume using depth for an annulus

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 Shape

Calculate mulch volume using depth for a triangle

Using measurements in feet:

Area (ft²) = 1/2 × Base × Height

Or, if you don't have the height of the triangle, but you have the lengths of each triangle side (sides a, b and c), use the below formula for triangle area.

Area = √ { [ (a + b + c) ÷ 2) ] × [ (a + b + c) ÷ 2) − a ] × [ (a + b + c) ÷ 2) − b ] × [ (a + b + c) ÷ 2) − c ] }

Volume (ft³) = Depth × Area

Volume in Cubic Yards (yd³) = Volume (ft³) ÷ 27

Trapezoid Shape

Calculate mulch volume using depth for a trapezoid

Using measurements in feet:

Area (ft2) = [(a + b) ÷ 2 ] × h

Volume (ft³) = Depth × Area

Volume in Cubic Yards (yd³) = Volume (ft³) ÷ 27

Frequently Asked Questions