Cubic Feet Calculator from Inches

This calculator converts a length, width, and height measured in inches into the equivalent volume in cubic feet. You enter the three dimensions in inches, and it returns the volume in cubic feet, along with the volume in cubic inches for reference. The result is the standard unit used in the US for shipping, construction, and appliance sizing.

Formula

The volume in cubic feet is calculated by multiplying the three dimensions in inches and then dividing by 1,728.

Volume (ft³) = (Length × Width × Height) ÷ 1,728

Where:

• Length, Width, Height are the three dimensions of the object, all measured in inches (in).
• 1,728 is the number of cubic inches in one cubic foot (12 × 12 × 12).

The same formula works with any unit as long as all three dimensions are in the same unit. If you measure in centimeters, divide by 28,316.8 to get cubic feet, or convert each dimension to feet first and multiply.

Worked Example

Using the default values from the calculator: Length = 24 in, Width = 12 in, Height = 6 in.

1. Multiply the three dimensions: 24 × 12 × 6 = 1,728 in³.
2. Divide by 1,728: 1,728 ÷ 1,728 = 1.00 ft³.

The calculator shows 1.00 ft³ and 1,728 in³. This is exactly the volume of a box that is 2 feet long, 1 foot wide, and 0.5 feet tall.

Why Use Cubic Feet?

Cubic feet is the standard volume unit for many everyday objects in the United States and Canada. Refrigerators, freezers, ovens, and washing machines are sized in cubic feet. Shipping companies charge by dimensional weight, which is often based on cubic feet. Construction materials like concrete, gravel, and soil are sold by the cubic yard (27 cubic feet). Knowing how to convert from inches to cubic feet lets you compare product sizes, estimate shipping costs, or plan a project without needing a separate conversion tool.

How to Measure in Inches

To get an accurate cubic feet value, measure the three external dimensions of the object in inches. Use a tape measure or ruler. For a rectangular box, measure the longest side (length), the side perpendicular to it (width), and the vertical side (height). Make sure all measurements are in inches, not feet or centimeters. If your object is not a perfect rectangle (like a cylinder or an irregular shape), this simple formula does not apply; you need a different volume formula.

For a cylinder, for example, the volume is π × radius² × height. If you measure the radius and height in inches, the result is in cubic inches, and you still divide by 1,728 to get cubic feet.

Common Mistakes and How to Avoid Them

• Mixing units: The most common error is entering one dimension in feet and others in inches. Always convert everything to inches first, or use the calculator with consistent units.
• Forgetting to divide by 1,728: Multiplying the three dimensions gives cubic inches, not cubic feet. The division is essential.
• Rounding too early: If you round each dimension to the nearest inch, you can lose accuracy. Keep at least one decimal place for small objects.
• Using external vs. internal dimensions: For shipping, use external dimensions. For storage capacity (like a cooler), use internal dimensions. The difference can be significant.

When to Use This Calculator

Use this calculator whenever you have dimensions in inches and need a volume in cubic feet. Common situations include:

• Estimating the size of a moving box or shipping carton.
• Comparing the capacity of appliances like refrigerators or freezers.
• Calculating the volume of a planter box or aquarium (though aquariums are often measured in gallons; multiply cubic feet by 7.48052 to get US gallons).
• Determining how much concrete or soil to order for a rectangular form.
• Checking the volume of a package against a carrier’s dimensional weight rules.

Remember that for shipping, carriers often use a divisor (like 139 or 166) to convert cubic inches to dimensional weight in pounds. This calculator gives you the physical volume, not the billable weight.

Limitations and Alternatives

This calculator assumes a perfect rectangular prism. It does not account for irregular shapes, rounded corners, or hollow interiors. For such objects, you may need to use water displacement (for small items) or break the object into simpler shapes and sum their volumes. Also, the calculator gives volume in cubic feet, but if you need cubic yards (for landscaping or concrete), divide the cubic feet result by 27. If you need liters, multiply cubic feet by 28.3168.

For measurements in other units, you can still use this calculator by first converting each dimension to inches. For example, 1 foot = 12 inches, 1 yard = 36 inches, 1 centimeter = 0.393701 inches.

Frequently Asked Questions

How many cubic inches are in a cubic foot?

There are 1,728 cubic inches in one cubic foot. This comes from cubing the conversion factor: 12 inches per foot × 12 × 12 = 1,728. So to convert cubic inches to cubic feet, divide by 1,728.

Can I use this calculator for a cylinder?

No, this calculator is only for rectangular boxes. For a cylinder, use the formula π × radius² × height, where radius and height are in inches. The result will be in cubic inches; divide by 1,728 to get cubic feet.

What is the difference between cubic feet and square feet?

Cubic feet measure volume (three-dimensional space), while square feet measure area (two-dimensional surface). To get square feet, you multiply length by width only. To get cubic feet, you multiply length by width by height. For example, a 2 ft × 3 ft floor is 6 square feet; if it is 1 ft high, it is 6 cubic feet.

How do I convert cubic feet to gallons?

One cubic foot equals 7.48052 US liquid gallons. Multiply the cubic feet value by 7.48052 to get gallons. For imperial gallons, multiply by 6.22884. This is useful for aquariums or water tanks.

Why do shipping companies use cubic feet?

Shipping carriers use volume to calculate dimensional weight, which is the lower of actual weight and volumetric weight. This ensures that large, lightweight packages are charged fairly. The formula varies by carrier, but it always involves the package’s cubic volume.

What if my measurements are in feet and inches?

Convert everything to inches first. For example, 2 ft 6 in = 30 inches (2 × 12 + 6). Then use the calculator. Alternatively, convert each dimension to feet (6 in = 0.5 ft) and multiply, but be careful not to mix units.

Related

• 3 in Fraction Calculator: Solve Mixed Numbers Fast
• 28 mm to Fraction Calculator: Quick Conversion
• 2 Pounds to Ounces Calculator: Quick Conversion

in length | Length | in | 24 | 0
in width | Width | in | 12 | 0
in height | Height | in | 6 | 0
out cuft | Cubic feet | ft³ | length * width * height / 1728 | 2
out cuin | Cubic inches | in³ | length * width * height | 0