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Calculate Cubic Feet of a Rectangle

The cubic feet calculator finds cubic feet of volume given dimensions. Whether you have a room, box or storage unit, or you're buying soil for your garden, use the cubic feet calculator to find the cubic footage of your space or material.

How to Use the Cubic Feet Calculator

If you work with mulch, concrete slabs, home insulation, or HVAC ductwork you'll need to calculate cubic feet of volume for material planning and purchasing.

If you've landed here for engineering or academic purposes, you might be looking to calculate the volume of a special shape like a pyramid or a cylinder.

Use this calculator to solve both practical and specialized cubic feet volume calculations. Select the name or the shape of the space you're measuring and enter dimensions. The cubic feet calculator supports both US and metric measurements. You can calculate volume for:

• Room
• Box
• Storage unit
• Tank
• Rectangle
• Cube
• Cylinder (tube shape)
• Capsule (tube with rounded end)
• Triangular prism
• Pyramid
• Sphere (ball shape)
• Hemisphere (half-ball shape)
• Cone
• Conical frustum (cone with the point sliced off)

Answers are listed in cubic feet, but also cubic yards, cubic meters and cubic inches. We also provide equivalent liquid volumes like gallons, quarts, and liters. This calculator functions like a converter in that you can calculate volume in cubic feet and see the equal volume in other units of measure.

For irregular shapes, divide the area into smaller sections made up of shapes you can work with. Calculate cubic feet for each section and add them together.

Estimate costs per cubic foot, yard and meter in the Optional Cost Calculation box.

This calculator makes it easy to find cubic feet for many contexts including concrete slabs, insulation, closet layouts, attic or basement refinishing, ductwork and ventilation projects, buying mulch or topsoil, container gardening, storage space, shipping or moving, or sizing appliances.

What is a Cubic Foot?

A cubic foot is a measure of volume. One cubic foot of volume is the amount of space occupied by a cube that is one foot long on each side, length, width and height. The symbols for cubic feet are ft³ or cu ft. Cubic feet is a standard unit of measure in the United States and United Kingdom.

To visualize, a cubic foot is about the size of a standard file box.

Converting Cubic Feet to Other Units

Use this table to look up conversion factors when converting from cubic feet to other units of measure.

Note about cubic feet to square feet: Because cubic feet measures volume and square feet measures area, they don't directly convert. However, you can divide cu ft by the height in feet to get square feet.

Why Measure Cubic Feet?

Cubic feet measures volume which is the amount of 3-dimensional space occupied by an object or material. The formula for volume is length × width × height.

If you think about measuring area, which is length × width, the result is a flat, 2-dimensional plane kind of like a piece of poster paper.

Cubic feet measurements take area an add another dimension - height. When you multiply an area of square footage by the third dimension height, you get a measure of volume. Volume is a useful way to measure a solid like a stack of poster paper, a liquid like a tank full of water, or a gas like a room full of air.

Calculate Cubic Feet for Moving

Estimating the space occupied by boxes, containers and appliances helps you choose the right size truck or storage space. For accurate results, calcluate the cubic feet of individual items with the cubic feet calculator and then add the values together.

While moving companies typically take an inventory of larger items, moving boxes tend to come in a few general sizes. Be sure to confirm box sizes before you purchase them:

• Extra small: 1 cu ft
• Small: 1.5 cu ft
• Medium: 3 cu ft
• Large: 4.5 cu ft
• Extra large: 6 cu ft

Example: You're renting a storage unit and need to calculate the total cubic feet of your boxes. You have 10 small boxes (each 16" × 12" × 12"), 8 medium boxes (18" × 18" × 16") and 5 large boxes (24" × 18" × 18").

1. Calculate cubic inches for each box type
   • Small box: 16 × 12 × 12 = 2,304 cubic inches
   • Medium box: 18 × 18 × 16 = 5,184 cubic inches
   • Large box: 24 × 18 × 18 = 7,776 cubic inches
2. Convert to cubic feet, dividing by 1,728
   • Small box: 2,304 ÷ 1,728 = 1.33 cubic feet
   • Medium box: 5,184 ÷ 1,728 = 3.0 cubic feet
   • Large box: 7,776 ÷ 1,728 = 4.5 cubic feet
3. Multiply the cubic feet value for each box by the number of each box you have
   • Small boxes: 1.33 × 10 = 13.3 cubic feet
   • Medium boxes: 3.0 × 8 = 24 cubic feet
   • Large boxes: 4.5 × 5 = 22.5 cubic feet
4. Add the values together for total cubic feet
   • 13.3 cu ft + 24 cu ft + 22.5 cu ft = 59.8 cubic feet

You need a small storage unit that is at least 60 cubic feet. In this scenario, consider a larger unit to allow space for walking around and accessing your items.

Calculate Cubic Feet for Landscaping Material (Mulch, Gravel, Soil)

Calculating volume in cubic feet for mulch, soil and gravel helps with accurate budgeting, avoiding material shortages and over-ordering, and ensures proper depth for your project.

Example: You are mulching a flower bed and you want a layer of mulch that is 3 inches deep.

1. Measure the area:
   • Length is 20 feet
   • Width is 8 feet
2. Convert your depth to feet:
   • You want a depth of 3 in
   • 3 in ÷ 12 = 0.25 feet
3. Calculate cubic feet by multiplying length, width and depth:
   • 20 ft × 8 ft × 0.25 ft = 40 cubic feet
4. Convert to bags/yards as an optional step:
   • Most mulch bags are 2 cubic feet: 40 ÷ 2 = 20 bags
   • Find cubic yards by dividing by 27: 40 ÷ 27 = 1.48 cubic yards (bulk delivery)

You need 40 cubic feet for your flower bed. Remember to add 5–10% extra for settling and waste. See our mulch calculator for an in-depth look at calculating mulch given the size and shape of your area.

How to Calculate Cubic Feet: Volume Formula for Common Shapes

Below are volume formulas for common shapes. For cubic feet, use all measurements in feet.

Frequently Asked Questions