How this calculator works
A US liquid gallon is exactly 231 cubic inches. The cubic inch is the cube of the exact 0.0254 m inch. The US liquid, imperial and US dry gallon are different volumes. The table labels all three definitions, while the main result starts with US liquid gallons. The dry gallon here means four US dry quarts, derived from the exact 2,150.42 in3 bushel.
Formula
US liquid gallons = cubic inches / (231); imperial gallons = volume in m3 / 0.00454609; US dry gallons = volume in m3 / 0.00440488377086.
Worked example
462 in3 is exactly 2 US liquid gallons. Conversely, 0.5 US liquid gallon is exactly 115.5 in3.
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Frequently asked questions
Which gallon does the main result use?
US liquid gallons by default. Select imperial or US dry gallons explicitly when needed.
Why is the imperial result smaller?
An imperial gallon is larger than a US liquid gallon, so fewer imperial gallons represent the same volume.
Can I convert a tank volume?
Yes. Enter the usable liquid volume. Nominal tank capacity and actual fill volume may differ.