US Gallons to Cubic Inches (gal to in³)
1 US gallon equals 231 cubic inches exactly.
How to convert US gallons to cubic inches
To convert US gallons to cubic inches, multiply the number of US gallons by 231. This factor is exact. To go the other way, multiply cubic inches by 0.004329004329 (rounded).
cubic inches = US gallons × 231
Example: 10 US gallons = 2,310 cubic inches.
Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.
About these units
US Gallon (gal)
Exactly 231 cubic inches or 3.785411784 liters (128 US fluid ounces). About 17% smaller than the imperial gallon.
The US gallon is a survivor of English wine trade. Around 1706, a statute in Queen Anne's reign fixed the wine gallon at exactly 231 cubic inches, settling confusion among the competing gallons for wine, ale and corn. British colonies in North America used that wine gallon, and in 1824 Britain replaced all its gallons with a new imperial one while the United States kept the old measure. It was adopted as the legal US standard in 1836 and is still defined as exactly 231 cubic inches, or 3.785411784 liters.
That makes the US gallon about 17 percent smaller than the imperial gallon, a difference that explains why American and British fuel-economy figures cannot be compared directly. Everyday uses are milk jugs, paint cans and gasoline pumps. One gallon divides evenly into four quarts, eight pints, sixteen cups and 128 fluid ounces. A gallon of water weighs a little over 8 pounds, an easy figure to remember when loading a car with water jugs.
1 US gallon = 3.785411784 liters (exactly).
Sources: Wikipedia: Gallon; NIST SP 811, Appendix B.8: conversion factors for volume
Cubic Inch (in³)
Exactly 16.387064 mL. Used for engine displacement in the US and for small mechanical parts.
Cubic inch is a unit defined by a ruler. Take an inch, build a cube, and its volume is exactly 16.387064 milliliters under the modern definition of the inch as 25.4 millimeters. Its main role in history is as the building block behind other US volumes: the US gallon is defined as 231 cubic inches, so a cubic inch is exactly 1/231 of a gallon. Even the 42-gallon oil barrel works out to precisely 9,702 of them.
The cubic inch survives most visibly in American engines, which are abbreviated c.i.d. for cubic inch displacement, while the rest of the world and many modern automakers speak in liters. A 5.7 liter engine is about 350 cubic inches, a conversion made easy by the exact factor of 16.387064. Small mechanical parts are also sized in cubic inches in North America.
1 cubic inch = 0.016387064 liters (exactly).
Sources: Wikipedia: Cubic inch; NIST SP 811, Appendix B.8: conversion factors for volume
Related conversions
- Cubic inches to US gallons (reverse)
- US gallons to liters
- US gallons to milliliters
- US gallons to US cups
- US gallons to US fluid ounces
- US gallons to cubic meters
- US gallons to cubic centimeters
- US gallons to US quarts
- US gallons to US pints
- US gallons to US tablespoons
- US gallons to US teaspoons
- US gallons to metric cups
- US gallons to metric tablespoons
- Liters to cubic inches
- Milliliters to cubic inches
- US cups to cubic inches
- US fluid ounces to cubic inches
- Cubic meters to cubic inches
- Cubic centimeters to cubic inches
- US quarts to cubic inches
- US pints to cubic inches
- US tablespoons to cubic inches
- US teaspoons to cubic inches
- Metric cups to cubic inches
- Metric tablespoons to cubic inches
See all volume units.