The answer to this question is going to depend on which country you are asking in. In the United States, there are 3.7854118 liters in one gallon. In the United Kingdom, there are 4.54609188 liters in one gallon. For clarity, we will be discussing the conversion from gallons to liters in the context of the United States.
1 US gallon = 3.7854118 L
1 L = 0.2641720524 US gallon
The Math Behind the Conversion
There are a few reasons for why there are 3.7854118 L in 1 US gallon. The first has to do with history and customary units. The second reason has to do with the metric system. Let’s explore both of these reasons a bit further.
Reasons for 3.7854118 L in 1 US Gallon
1) History and Customary Units
The gallon has been around for a very long time and it was originally used to measure things like ale and wine. Later on, it started being used to measure other liquids such as milk and gasoline. The thing is, there have been many different versions of the gallon throughout history. For example, in 1688, an English court defined the imperial gallon as 10 pounds of water at 62 degrees Fahrenheit that is enclosed in a cylinder that is 277.42 cubic inches big. While this might seem confusing, what is important to know is that the definition of a gallon has changed over time – especially when looking at different countries.
In 1824, the British Weights and Measures Act standardized various units including the imperial gallon which ended up being defined as exactly 4.54609188 liters or 10 pounds of water at 62 degrees Fahrenheit that is enclosed in a cylinder that is 277.42 cubic inches big (once again). As you can see, even though the size of an imperial gallon was standardized, it was still defined using both units of measurement – pounds and liters.
2) The Metric System
In 1901, Queen Victoria signed into law An Act to Authorize . . .the Use of Measurement Units Based Upon the Metric System and symbolized Great Britain’s switch from imperial to metric measurements (although they continued using some customary/imperial measurements until 1965). This helped establish equality between different types of measurements and made it easier for people to move between them without having to hold conversions in their heads or look them up constantly (like we have to do when converting from gallons to liters!). Nowadays, almost every country uses metric measurements although there are some holdouts like Myanmar and Liberia who continue using customary/imperial measurements – we’ll save that discussion for another day!
All this talk about gallons and liters might have you feeling a bit thirsty! If you’re anything like me, you now have an urge to go pour yourself a cold glass of water (or maybe something stronger after all this math!). I hope this article helped clear up any confusion surrounding how many liters are in one US gallon but if not or if you have any additional questions, please don’t hesitate to reach out or leave a comment below! Thanks for reading!