Gallons to Liters Converter

How to Convert Gallons to Liters

Converting gallons to liters is one of the most frequently needed volume conversions, especially when comparing fuel prices, following recipes, or sizing tanks and containers across different measurement systems. The conversion formula is simple and exact:

liters = US gallons × 3.78541

One US liquid gallon is defined as exactly 231 cubic inches, which works out to approximately 3.78541 liters. This factor is derived from the international definition of the inch (25.4 mm) and the liter (one cubic decimeter = 1,000 cm³).

To convert in the opposite direction—liters to gallons—simply divide by the same factor:

US gallons = liters ÷ 3.78541

For example, if you need to know how many liters are in 5 US gallons: 5 × 3.78541 = 18.927 liters. Conversely, a 20-liter jerry can holds 20 ÷ 3.78541 ≈ 5.28 US gallons.

Our calculator above handles both conversions simultaneously. Enter a gallon value, a liter value, or both, and the results appear instantly. This makes it easy to do quick comparisons—for instance, checking whether a 5-gallon bucket or a 20-liter container holds more (the 20-liter container holds slightly more, by about 1.07 liters).

US Gallon vs. Imperial Gallon

One of the most common sources of confusion in gallon-to-liter conversion is the difference between the US gallon and the Imperial (UK) gallon. Despite sharing the same name, they represent different volumes:

The Imperial gallon is approximately 20% larger than the US gallon. This difference has real-world consequences: a car advertised as getting 40 miles per gallon in the UK is actually more fuel-efficient than one rated at 40 mpg in the US, because the UK gallon is bigger. Specifically, 40 mpg (UK) ≈ 48 mpg (US).

Canada officially uses the metric system but historically used Imperial gallons. Older Canadian references to "gallons" mean Imperial gallons, while modern usage typically specifies liters. When converting, always confirm which gallon is being referenced.

This converter uses the US liquid gallon (3.78541 L) by default, as it is the most commonly searched conversion. If you need the Imperial gallon, multiply liters by 0.21997 or divide by 4.54609.

Gallons to Liters Conversion Table

This reference chart provides quick gallon-to-liter conversions for commonly used volumes. Keep it bookmarked for everyday use.

Practical Applications of Gallons to Liters Conversion

The gallon-to-liter conversion is relevant across a wide range of industries and daily activities. Here are the most common use cases:

Fuel Economy and Gas Prices. Americans measure fuel economy in miles per gallon (mpg), while most of the world uses liters per 100 kilometers (L/100 km). To compare: if a car gets 30 mpg (US), that equals about 7.84 L/100 km. When traveling abroad, converting gas prices from dollars per gallon to euros per liter (or vice versa) helps you budget accurately. A US price of $3.50/gallon equals about $0.92/liter.

Cooking and Recipes. American recipes measure liquids in cups, pints, quarts, and gallons (1 gallon = 4 quarts = 8 pints = 16 cups). International recipes use milliliters and liters. When scaling a recipe that calls for "1/2 gallon of stock," you need approximately 1.89 liters. Conversely, a European recipe calling for 2 liters of water equals about 0.53 US gallons or just over half a gallon.

Aquariums and Fish Tanks. Fish tanks sold in the US are sized in gallons (10-gallon, 20-gallon, 55-gallon), while filters, heaters, and water treatment chemicals may be rated in liters. A 10-gallon tank holds approximately 37.85 liters, and a 55-gallon tank holds about 208.2 liters. Correct conversion ensures you dose water treatments properly—overdosing or underdosing can harm fish.

Swimming Pools and Hot Tubs. Pool volume calculations often start in gallons (a typical residential pool holds 15,000–30,000 gallons). Chemical treatment guides from international manufacturers may specify dosing per 1,000 liters. Converting between the two ensures proper chlorine levels and water chemistry.

Brewing and Winemaking. Homebrewing recipes from the US use gallon-based batch sizes (typically 5 gallons), while European recipes use liters. A standard 5-gallon batch is approximately 18.93 liters. Converting accurately ensures the right hop, yeast, and grain ratios for the intended batch size.

International Shipping. Liquid cargo volumes may be specified in gallons or liters depending on the origin and destination. Accurate conversion prevents under- or over-filling containers and ensures compliance with customs declarations and weight restrictions.

Agriculture. Irrigation volumes, pesticide dilution rates, and fertilizer concentrations cross gallon-liter boundaries frequently, particularly in North American agriculture where equipment may use gallon-calibrated meters but chemical labels provide metric dosing instructions.

History of the Gallon

The gallon has a surprisingly complex history. The word "gallon" derives from the Old Northern French word galon, itself possibly from the Latin galleta (a pail or bucket). Over the centuries, multiple gallons coexisted in England and its colonies, leading to considerable confusion.

In medieval England, different gallons were used for different commodities. The wine gallon (about 231 cubic inches) was used for wine and spirits, while the ale gallon (about 282 cubic inches) was used for beer, and the corn gallon (about 268–272 cubic inches) was used for dry goods like grain.

When the United States gained independence, it adopted the Queen Anne wine gallon of 231 cubic inches as its standard liquid gallon. Meanwhile, in 1824, the United Kingdom standardized on the Imperial gallon, defined as the volume of 10 pounds of water at 62 °F. This works out to approximately 277.42 cubic inches or 4.54609 liters—significantly larger than the US gallon.

The metric system, developed in France in the 1790s, introduced the liter as a unit of volume. Originally defined as one cubic decimeter (1,000 cm³), the liter provided a simple, decimal-based alternative to the bewildering variety of gallons, pints, and quarts used across Europe and the Americas.

Today, the liter is used as the standard volume unit in virtually every country except the United States, where gallons, quarts, and fluid ounces remain dominant for consumer products. Even in the US, scientific and medical contexts almost exclusively use liters and milliliters.

Liters to Gallons Conversion Table

For convenience, here is the reverse lookup—common liter values converted to US gallons.

Tips for Quick Mental Conversion

When you do not have a calculator handy, these approximations can help you estimate gallon-to-liter conversions quickly:

• Gallons to liters: Multiply by 4, then subtract about 5%. Example: 10 gallons × 4 = 40, minus 5% (2) ≈ 38 liters. Actual: 37.85 L. Close enough for most purposes.
• Liters to gallons: Divide by 4, then add about 5%. Example: 20 liters ÷ 4 = 5, plus 5% (0.25) ≈ 5.25 gallons. Actual: 5.28 gallons.
• The "4-to-1" rule: Remember that 1 gallon is roughly 4 liters (actually 3.785). This gives you a ballpark figure instantly. Four 1-liter bottles is just a hair over one gallon.
• Fuel price shortcut: To convert $/gallon to $/liter, divide by 3.785. To go from €/liter to $/gallon, multiply by 3.785 and adjust for the exchange rate.

These mental shortcuts are accurate to within 5%, which is sufficient for everyday estimation, travel budgeting, and casual cooking.