Cubic Feet to Gallons Calculator & Formula

This calculator converts a volume in cubic feet to US liquid gallons. Enter the cubic feet value, and you get the equivalent gallons instantly, along with the conversion factor used. The formula is simple: 1 cubic foot equals 7.48052 US gallons.

Formula

The conversion uses the exact relationship between the two units:

Gallons = Cubic Feet × 7.48052

Where:

• Cubic feet (ft³) is the volume you want to convert.
• 7.48052 is the number of US liquid gallons in one cubic foot.

This factor comes from the definitions: 1 US gallon = 231 cubic inches, and 1 cubic foot = 1,728 cubic inches. Dividing 1,728 by 231 gives 7.48052.

Worked Example

Using the default value of 10 cubic feet:

1. Start with 10 ft³.
2. Multiply by 7.48052: 10 × 7.48052 = 74.8052.
3. Round to 2 decimal places: 74.81 gallons.

So 10 cubic feet equals 74.81 US liquid gallons. If you have a smaller volume, say 2 cubic feet, the result is 2 × 7.48052 = 14.96 gallons.

Why Use Cubic Feet to Gallons?

You might need this conversion for everyday tasks like measuring water in a fish tank, estimating paint or concrete needs, or understanding the capacity of a container. Many product labels list volume in gallons, but the physical dimensions of a space are often measured in feet. For example, a storage box that is 2 ft × 1 ft × 1.5 ft has a volume of 3 ft³. To know how many gallons of liquid it can hold, you multiply 3 × 7.48052 = 22.44 gallons.

US vs. Imperial Gallons

One common mistake is confusing US gallons with imperial gallons. The UK imperial gallon is larger: 1 imperial gallon = 277.42 cubic inches, so 1 cubic foot equals about 6.2288 imperial gallons. This calculator uses US liquid gallons, which are the standard in the United States and for most consumer products like beverages and aquariums. If you need imperial gallons, multiply the cubic feet by 6.2288 instead.

How to Measure Cubic Feet

To measure a space or container in cubic feet, multiply its length, width, and height in feet. For example, a refrigerator compartment that is 3 ft wide, 2 ft deep, and 4 ft tall has a volume of 3 × 2 × 4 = 24 ft³. If your measurements are in inches, convert them to feet first by dividing by 12. Then apply the conversion to gallons.

Common Mistakes and Tips

• Using the wrong gallon: Always check whether you need US or imperial gallons. For US gallons, use 7.48052; for imperial, use 6.2288.
• Mixing units: Ensure all dimensions are in feet before multiplying. If you have inches, convert them to feet (e.g., 6 inches = 0.5 ft).
• Rounding too early: For precise work, keep the full factor (7.48052) until the final step. Rounding to 7.5 early can cause errors in large volumes.
• Forgetting to convert from cubic inches: If you have a volume in cubic inches, divide by 1,728 to get cubic feet first, then multiply by 7.48052.

Practical Applications

This conversion is useful in many real-world situations:

• Aquariums: A 4 ft × 1.5 ft × 2 ft tank holds 12 ft³, which is about 89.77 gallons.
• Fuel and liquid storage: A 5 ft × 5 ft × 5 ft cube holds 125 ft³, or 935.07 gallons of water.
• Construction materials: Concrete is often ordered in cubic yards, but if you have a cubic foot measurement, converting to gallons can help estimate mixing water.
• Shipping and freight: Some shipping costs depend on volume; knowing gallons can help with liquid cargo.

Frequently Asked Questions

How many gallons are in a cubic foot?

There are exactly 7.48052 US liquid gallons in one cubic foot. This is a fixed conversion factor based on the definition of the gallon (231 cubic inches) and the cubic foot (1,728 cubic inches).

Can I convert gallons to cubic feet with this calculator?

Yes, you can reverse the formula. Divide the number of gallons by 7.48052 to get cubic feet. For example, 50 gallons ÷ 7.48052 = 6.68 ft³.

What is the difference between US and imperial gallons?

The US liquid gallon is about 3.785 liters, while the imperial gallon is about 4.546 liters. Because the imperial gallon is larger, there are fewer imperial gallons in a cubic foot (6.2288) compared to US gallons (7.48052).

How do I calculate gallons from inches?

First convert inches to feet by dividing by 12. Then multiply length × width × height to get cubic feet. Finally, multiply by 7.48052 to get US gallons. For example, a box 24 in × 12 in × 12 in = 2 ft × 1 ft × 1 ft = 2 ft³ = 14.96 gallons.

Is this conversion accurate for all liquids?

Yes, the conversion is based on volume, not on the type of liquid. Whether you measure water, milk, or oil, the volume in gallons is the same for a given cubic foot measurement. However, weight will differ because density varies.

Why is the conversion factor 7.48052 and not a round number?

Because the gallon is defined as 231 cubic inches, and the cubic foot is 1,728 cubic inches. Dividing 1,728 by 231 gives a non-terminating decimal, so we round to 7.48052 for practical use.

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in cf | Cubic feet | ft³ | 10 | 0
out gal | US liquid gallons | gal | cf * 7.48052 | 2