Cubic Feet to Gallons Calculator: Convert Volume

This cubic feet to gallons calculator converts a volume in cubic feet (ft³ or cf) into US liquid gallons. Enter the volume in cubic feet to get the equivalent gallons, with the conversion formula and a worked example below.

Formula

To convert cubic feet to US liquid gallons, multiply the volume in cubic feet by the number of US gallons in one cubic foot:

Gallons = cubic feet × 7.48051948052

• Gallons is the volume in US liquid gallons (US gal).
• Cubic feet is the volume in cubic feet (ft³, sometimes written cf).
• 7.48051948052 is the conversion factor: one cubic foot is exactly 1,728 cubic inches, and one US liquid gallon is exactly 231 cubic inches. Therefore, 1,728 ÷ 231 = 7.48051948052… US gallons per cubic foot.

The calculator also reports liters using liters = cubic feet × 28.316846592. One cubic foot is approximately 28.3168 liters. The gallon result is US liquid gallons, not Imperial gallons.

Worked Example

Using the calculator’s default input of 1 cubic foot:

1. Start with 1 ft³.
2. Multiply by the conversion factor: 1 × 7.48051948052 = 7.48051948052 US gal.
3. Round to two decimal places, as the calculator does: 7.48 US gal.

The same volume in liters is 1 × 28.316846592 = 28.316846592 L, or 28.32 L to two decimal places.

What “cf” Means and When to Convert

In volume measurements, “cf” commonly abbreviates cubic feet; it is also written as ft³. A cubic foot is the volume of a cube whose sides are each one foot long. Because a foot is a unit of length, cubic feet measure three-dimensional space—not surface area or the length of a pipe.

Converting cubic feet to gallons is useful when a container, tank, pool, storage space, or water-flow calculation is expressed in cubic feet but you need a liquid-capacity figure. The conversion changes the unit, not the physical volume. It does not account for a container’s shape, how full it is, or usable capacity after internal fittings and free space.

• Use cubic feet for a volume already stated in ft³, such as a rectangular space measured in feet.
• Use gallons when comparing liquid capacity with a figure stated in US gallons.
• Use liters when working with metric capacity or a label stated in liters.

If you have length, width, and height rather than a volume, first calculate the volume. For a rectangular space with all dimensions in feet, multiply length × width × height to get cubic feet. If measurements are in inches, either convert each dimension to feet before multiplying or calculate cubic inches and divide by 1,728.

US Gallons, Imperial Gallons, and Liters

The word “gallon” can mean different units. This calculator uses the US liquid gallon, the common US customary unit for liquid capacity. An Imperial gallon, used in some contexts in the United Kingdom and elsewhere, is larger. One cubic foot is approximately 6.23 Imperial gallons, rather than 7.48 US gallons.

For metric comparison, one cubic foot is approximately 28.32 liters. One US liquid gallon is approximately 3.785 liters, while one Imperial gallon is approximately 4.546 liters. These distinctions matter when reading equipment specifications, historical references, or measurements from another country. Check which gallon a source means before comparing capacities.

For example, 10 cubic feet equals about 74.81 US gallons, 62.34 Imperial gallons, or 283.17 liters. The underlying volume is the same; only the unit changes.

How to Use the Result Correctly

The calculator rounds its displayed answers to two decimal places. Treat that as a convenient presentation, not a change in the actual volume. For a small amount, rounding may make a more noticeable relative difference; for a large tank, the displayed hundredth of a gallon may be more precision than the measurements justify.

For practical estimates, the input measurements often limit accuracy. If a tank’s dimensions are approximate, reporting a result to many decimal places does not make the estimate more reliable. Keep more digits during intermediate calculations when needed, then round the final result to a sensible level for the task.

Also distinguish total geometric volume from the amount of liquid actually present. A tank may not be filled to its top, and a vessel’s stated dimensions may refer to its outside rather than its inside. For an irregular vessel, dimensions alone may not provide an accurate capacity; use a reliable capacity specification or measure the actual volume.

Common Conversion Mistakes and Limits

• Using the wrong gallon: 7.48 is the approximate US-gallon factor. It is not the Imperial-gallon factor.
• Confusing cubic feet with square feet: ft² measures area; ft³ measures volume. Area alone cannot be converted to gallons without a depth.
• Mixing units in a dimension calculation: convert all lengths to the same unit before multiplying. For example, feet × inches × feet does not directly produce cubic feet.
• Multiplying by 7.48 when converting the other way: to convert US gallons to cubic feet, divide gallons by 7.48051948052.
• Assuming a calculated capacity is fillable capacity: shape, internal components, and the intended fill level can reduce the usable amount.

This is a unit conversion, not a water-use, flow-rate, or container-sizing calculation. Converting a flow rate requires a time unit as well—for example, gallons per minute cannot be inferred from cubic feet alone. The calculator also does not determine how much liquid a space holds unless the input cubic-foot volume is already known or correctly calculated.

Frequently Asked Questions

How many gallons are in one cubic foot?
One cubic foot contains approximately 7.48 US liquid gallons. In metric units, it is approximately 28.32 liters.

How do I convert cubic feet to gallons?
Multiply the number of cubic feet by 7.48051948052 for US liquid gallons. For example, 5 ft³ × 7.48051948052 is about 37.40 US gallons.

How many cubic feet are in a gallon?
One US liquid gallon is approximately 0.13368 cubic feet. Divide a US-gallon amount by 7.48051948052 to convert it to cubic feet.

Does this calculator use US or Imperial gallons?
It uses US liquid gallons. One cubic foot is about 7.48 US gallons or 6.23 Imperial gallons, so choose the factor that matches the unit required.

Can I calculate gallons from a tank’s dimensions?
Yes, if the tank is rectangular and its internal length, width, and height are known in feet: multiply those dimensions to get ft³, then multiply by 7.48051948052. For other shapes, use an appropriate volume formula or a reliable capacity measurement.

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in cf | Volume | ft³ | 1 | 0 | 100000000
out gal | Volume | US gal | cf * 7.48051948052 | 2
out l | Volume | L | cf * 28.316846592 | 2