Cubic Feet Calculator Explained

The cubic feet calculator finds the volume of a space or object measured in cubic feet. It works for rooms, boxes, storage units, tanks and standard geometric shapes such as cylinders, spheres, cones and pyramids. Enter the dimensions of your space in any unit, including inches, yards, millimeters, centimeters or meters, and the calculator converts everything to feet before computing volume.

A cubic foot is a unit of volume equal to a cube measuring one foot on every side, written as ft3 or cu ft. One cubic foot equals 1728 cubic inches and about 0.0370 cubic yards. Cubic feet is widely used in the United States for describing the size of rooms, appliances, shipping containers and bulk materials like soil, mulch and gravel.

How to Use This Calculator

Select the shape that matches your project from the dropdown menu, then enter the required dimensions. For a rectangular room or box, enter the length, width and height. For a cylinder or sphere, enter the radius and height where applicable. Choose the measurement unit for each dimension and the calculator will automatically convert your inputs to feet before finding the cubic footage.

After entering your values, press Calculate or hit Enter to see the volume displayed in cubic feet, cubic yards, cubic meters, cubic inches and gallons. Use the Clear button to reset every field and start a new calculation.

Calculate Cubic Feet for Moving and Storage

Calculating cubic feet for moving helps you choose the right size truck or storage unit by adding up the volume of every box and item you plan to move. Measure the length, width and height of each box in feet, multiply the three numbers together, then add the results for all boxes to get your total cubic footage.

For example, a box measuring 16 inches by 12 inches by 12 inches converts to 2304 cubic inches. Dividing by 1728 gives 1.33 cubic feet per box. Ten boxes of this size equal 13.3 cubic feet. Repeat this process for each box size and sum the totals to estimate the space you need.

Calculate Cubic Feet for Mulch, Soil and Gravel

Calculating cubic feet for landscaping materials such as mulch, soil and gravel ensures you order the correct amount without running short or overspending. Measure the length and width of the area in feet, convert the desired depth from inches to feet by dividing by 12, then multiply length, width and depth together.

For instance, a flower bed that is 20 feet long and 8 feet wide with a 3 inch mulch layer requires 20 multiplied by 8 multiplied by 0.25 feet, which equals 40 cubic feet. Since most mulch bags hold 2 cubic feet, you would need about 20 bags, or roughly 1.48 cubic yards if ordering in bulk.

Calculate Cubic Feet for HVAC and Room Air Volume

Calculating cubic feet for HVAC sizing tells installers how much air volume a heating or cooling system needs to handle. Multiply the room’s length, width and ceiling height in feet to get the room volume in cubic feet, then use this figure alongside BTU requirements, which typically range from 20 to 25 BTUs per cubic foot for air conditioning.

Volume Formulas by Shape

Volume formulas for common shapes are listed below. For results in cubic feet, enter all dimensions in feet before applying the formula.

• Rectangle, room or box: Volume equals length times width times height (V = l x w x h)
• Cube: Volume equals the side length cubed (V = a3)
• Cylinder: Volume equals pi times radius squared times height (V = pi r2 h)
• Sphere: Volume equals four thirds times pi times radius cubed (V = 4/3 pi r3)
• Hemisphere: Volume equals two thirds times pi times radius cubed (V = 2/3 pi r3)
• Cone: Volume equals one third times pi times radius squared times height (V = 1/3 pi r2 h)
• Pyramid: Volume equals one third times length times width times height (V = 1/3 l w h)
• Triangular prism: Volume equals the area of the triangular base times the prism length

Frequently Asked Questions About Cubic Feet