How many liters are there in a gallon?
There are 3.78 liters in a US gallon and 4.54 liters in an imperial gallon (UK).
Here is how:
For US:
In United States, 1 gallon has a capacity of 128 US fluid ounces (3785.41 mL) and 1 liter is 33.814 US fluid ounces (1000 mL). That makes 128 / 33.814 = 3.785 liters in a gallon in US.
Here is another calculation:
By definition 1 gallon is 231 cubic inches and 1 liter equals to the volume of one kilogram of water (1000 mL or 61.0237 cubic inches), that makes 231 / 61.0237 = 3.785 liters in a gallon in US.
For Imperial System (UK):
In Imperial system 1 gallon has a capacity of 160 imperial fluid ounces (4546.09 mL) and 1 liter is 35.1951 imperial fluid ounces (1000 mL). That makes 160 / 35.1951 = 4.54 litres in an imperial gallon in UK.
How to convert from gallons to liters (litres)?
To convert from gallons to liters, multiply the number of gallons "x" by 3.78 for US and multiply by 4.54 for UK (Imperial system).
For example, to find out how many liters there are in a gallon and a half, multiply 1.5 by 3.78, that makes 5.67 liters in 1.5 gallons.
You may also use this volume units conversion tool to convert between US, imperial gallons and liters.
What is a gallon?
Gallon is an imperial and US Customary measurement system volume unit. 1 US fluid gallon is 128 US fluid ounces (3785.41 mL), 1 US dry gallon is 148.94 US fluid ounces (4404.68149 mL) and 1 imperial gallon is 160 imperial fluid ounces (4546.09 mL). The abbreviation is "gal".
Some facts about gallon:
1 US fluid gallon of water weighs about 8.34 lbs or 133.44 ounces or 3.785 kilograms (kilograms equals to 1 liter of water). 1 US fluid gallon of milk weighs about 8.6 pounds (it can be a bit lighter or heavier based on the fat percentage), or 137.6 ounces or 3.9 kilograms.
1 UK gallon of water weighs 10 lbs or 160 ounces or about 4.54 kilograms. 1 UK gallon of milk weighs about 10.3 pounds (it can be a bit lighter or heavier based on the fat percentage), or 164.8 ounces or 4.67 kilograms.
What is a liter (litre)?
Liter (litre) is a metric system volume unit. 1 liter is 1000 mL, 33.814 US fluid ounces and 35.1951 imperial fluid ounces. The abbreviation is "L".
The list for your reference:
1 US Fluid Gallon = 3.7854118 Liters
1 US Dry Gallon = 4.4048838 Liters
1 Imperial Gallon (UK) = 4.54609 Liters