Gallons to Liters Converter

How to convert gallons to liters

Converting gallons to liters is a single multiplication. The formula is gal × 3.78541 = L, which means one gallon equals 3.78541 L. Going the other way, one liter equals 0.264172 gal.

The calculator above applies this automatically as you type, but it is worth knowing the arithmetic if you need to sanity-check a figure or work one out without a device to hand.

Worked examples

7 gal to L: multiply 7 by 3.78541, which gives 26.49787 L.

45 gal to L: multiply 45 by 3.78541, which gives 170.34345 L.

250 gal to L: multiply 250 by 3.78541, which gives 946.3525 L.

Gallons to Liters conversion table

The values below are calculated with the same function as the converter above, so they agree to the digit. Use it as a quick reference when you need a rough figure without typing anything.

What is a gallon?

A US liquid gallon is exactly 3.785411784 liters and contains four quarts, eight pints, or 128 fluid ounces. The imperial gallon used in the UK is a different and larger unit at about 4.546 liters.

Where the gallon came from

The US gallon derives from the English wine gallon of 231 cubic inches, which the United States kept after independence. Britain replaced its own patchwork of gallons with the imperial gallon in 1824, defined as the volume of ten pounds of water, which is why the two diverged.

Where gallons are used today

Gallons measure fuel, milk, paint, and water in the United States. The roughly 20 percent difference between US and imperial gallons is a genuine trap when comparing fuel economy figures between American and British sources.

• A milk jug is 1 gallon
• A US car tank holds about 15 gallons
• A gallon of water weighs about 8.34 lb

What is a liter?

A liter is exactly one cubic decimeter, or 1,000 cubic centimeters. It is not technically an SI base unit but is accepted for use with SI and is universally understood.

Where the liter came from

The liter was defined in 1795 as the volume of a cube one tenth of a meter on each side. Between 1901 and 1964 it was briefly redefined as the volume of one kilogram of water, which made it very slightly larger; that definition was abandoned and the original cubic-decimeter one restored.

Where liters are used today

Liters measure drinks, fuel, engine displacement, and any household liquid across the metric world. Fuel economy outside North America is usually expressed as liters per 100 kilometers rather than distance per unit of fuel.

• A large water bottle is 1 L
• A car fuel tank holds about 50 L
• A bathtub holds roughly 150 L

When you actually need this conversion

gallons belong to the imperial / us customary system and liters to the metric (si) system, so this conversion turns up whenever information crosses between countries that measure differently.

Accuracy, precision, and rounding

The factor used here (gal × 3.78541 = L) is derived from an internationally agreed exact definition, so the conversion itself is not an approximation. The results above are shown to about eight significant figures, which is more precision than almost any practical use requires.

The sensible rule is to round the answer to roughly the same precision as the number you started with. If you measured to the nearest gallon, an answer carrying six decimal places is not more accurate, it just looks more accurate. For most everyday purposes one or two decimal places is plenty.

Common mistakes to avoid

Converting in the wrong direction

Multiplying when you should divide is by far the most common error, and it is easy to miss because the result is still a number in a believable range. A quick check: since one gallon is 3.78541 L, a gallon value should get larger when converted.

Using a rounded factor for a long calculation

Rounding the conversion factor before multiplying, then repeating that across many values, compounds the error. Convert with the full factor and round only the final answer.

Confusing US and imperial gallons

A US gallon is about 3.785 liters and an imperial gallon about 4.546, a difference of roughly 20 percent. This converter uses the US gallon. Fuel economy figures from British sources look better than American ones partly for this reason alone.

Converting gallons to liters in a spreadsheet or in code

A one-off answer is what the calculator above is for. When you have a whole column of figures, or you are writing something that has to do the conversion repeatedly, it is worth putting the formula in the tool you are already working in.

Excel and Google Sheets

With your gallon value in cell A1, put this in B1 and fill it down the column:

=A1 * 3.78541

Excel also ships a built-in CONVERT function that handles many unit pairs directly, but it does not cover every unit and its unit codes are easy to mistype. An explicit formula like the one above is harder to get wrong and shows its working.

Python

def gal_to_l(value):
    return value * 3.78541

print(gal_to_l(10))

JavaScript

const galToL = (value) => value * 3.78541;

console.log(galToL(10));

Store the factor as a named constant rather than typing 3.78541 at each call site. When a figure appears in three places it will eventually be updated in two of them.

The two measurement systems behind this conversion

This conversion sits on the fault line between the two measurement systems still in everyday use. The metric system was designed in one go in the 1790s as a coherent decimal scheme, where every unit relates to the next by a power of ten. The imperial and US customary systems grew instead by accretion over centuries, which is why their relationships are numbers like 12, 16, 5,280, and 43,560 rather than round ones.

Only three countries have not formally adopted the metric system: the United States, Liberia, and Myanmar. In practice the picture is messier than that, since the US uses metric units throughout science, medicine, and the military, while metric countries still buy screens and tires by the inch. That overlap is exactly why conversions like this one stay necessary.

More questions about gallons and liters

Is the conversion exact or approximate?

The underlying definition is exact, and the factor shown here (3.78541) is that definition expressed to the precision this page displays. For any everyday purpose the result is exact; only at very high precision would you need more digits of the factor.

Why does the answer have so many decimal places?

The converter shows a high-precision result so that it is never the limiting factor in your calculation. It is up to you to round to something sensible. A measurement taken with a tape measure does not become more accurate because the conversion carried six decimals.

Can I convert in the opposite direction on this page?

Yes. The swap button in the calculator reverses the conversion and carries the current result across as the new input, so you do not have to navigate anywhere or retype anything. The second table above also lists the reverse conversion directly.

Does anything get sent to a server?

No. The arithmetic runs in your browser with a few lines of JavaScript. Nothing you type is uploaded, logged, or stored, which also means the converter keeps working if your connection drops after the page has loaded.

Which figure should I use on an official form?

Use whatever precision the form asks for, and if it does not say, match the precision of the original measurement. For height, weight, and similar personal details, one decimal place is almost always sufficient and often more than is wanted.

Related volume conversions

If you need to go the other way as a starting point rather than as a swap, the Liters to Gallons converter is the mirror of this page: same factor, same tables, opposite direction. It is the more natural place to start when most of your figures are already in liters.

Volume is the category where American and metric recipes diverge most, so these related pairs tend to come up together:

• mL to Cups - Convert milliliters to cups instantly. Essential for cooking recipes and kitchen measurements.
• Cups to mL - Convert cups to milliliters instantly. Essential for baking and international recipes.
• CM to Inches - Convert centimeters to inches instantly. Enter any value and get the exact result in decimal inches.
• KG to LBS - Convert kilograms to pounds instantly. Perfect for fitness, cooking, and shipping calculations.
• Celsius to Fahrenheit - Convert Celsius to Fahrenheit instantly. Essential for weather, cooking, and science.
• MPH to KPH - Convert miles per hour to kilometers per hour instantly. Perfect for travel and speed limits.

For anything not listed here, the full converter directory covers over a hundred pairs across length, weight, temperature, volume, area, speed, pressure, energy, and more.

Quick reference

Why Use Our Gallons to Liters Converter?

Frequently Asked Questions