Gallons to Liters Converter

Gallons to Liters: the quick answer and formula

To convert gallons to liters, multiply the number of US gallons by 3.78541. So 1 gallon is about 3.785 liters, 5 gallons is roughly 18.93 liters, and 10 gallons is about 37.85 liters. Enter any gallon value in the converter above and the liter result appears instantly — free, browser-based, and with no signup.

As with fluid ounces, the gallon is not a single unit worldwide. A US liquid gallon is 3.78541 liters, while a UK (imperial) gallon is larger at 4.54609 liters. This page uses the US gallon by default since it is the more common search, but the table below shows both so you can match a fuel pump, recipe, or container label from either country. You will also find the formula, a worked example, and the conversions people look up most often.

The gallon is a US customary and imperial unit of volume; the liter is the metric unit used for fuel, drinks, and containers almost everywhere outside the United States. Because the two systems sit side by side in fuel pricing, vehicle specs, and shipping, converting gallons to liters is one of the most practical everyday conversions there is. The difference between the US and imperial gallon is large — about 20 percent — so unlike many conversions, picking the wrong gallon here produces a noticeably wrong answer, not just a rounding wobble. That makes it worth being deliberate about which gallon your source uses.

How to use the Gallons to Liters converter

This gallons to liters converter is built for fast, repeatable lookups.

1. Enter the volume in gallons in the input field.
2. Read the result in liters, which updates as you type.
3. Use decimals for partial amounts — 2.5 gallons converts to about 9.46 liters.
4. Copy the answer, or clear the field and convert another value.

For the reverse direction, use the Liters to Gallons converter. People often keep both open as a combined gallons to liters and liters to gallons converter when comparing fuel economy or tank sizes.

Formula and a worked example

The conversion is a single multiplication: liters = US gallons × 3.78541. For imperial measurements, swap the factor to 4.54609. Both are fixed constants, so the only rounding happens in your final answer.

Walk through 5 gallons step by step (US):

1. Start with the value in gallons: 5.
2. Multiply by 3.78541: 5 × 3.78541 = 18.92705.
3. Round as needed: 5 US gallons = 18.93 liters.

The table below lists worked results for common volumes, with the UK equivalent alongside so the difference is clear.

A quick estimate: multiply US gallons by 3.8 (or just by 4 for a rough ceiling). For 5 gallons that gives about 19 liters, close to the exact 18.93. Fine for a mental check, but use the full factor for fuel, chemistry, or anything billed by volume.

US versus imperial gallons in practice

The gap between the two gallons is big enough to change real decisions. A US gallon is 3.78541 liters; an imperial gallon is 4.54609 liters — about 0.76 liters more per gallon. Fill a notional 10-gallon tank and the US reading is 37.85 liters while the imperial reading is 45.46 liters, a difference of more than seven and a half liters. That is why fuel-economy figures look so different across the Atlantic: a car rated at, say, 30 miles per US gallon and one rated at 30 miles per imperial gallon are not equally efficient, because the imperial gallon holds more fuel.

As a rule of thumb, fuel and volumes quoted in the United States use the US gallon, while UK and older Commonwealth sources use the imperial gallon. Canada switched to liters for fuel years ago, but you still see Canadian recipes and older references in imperial gallons, which is why "canadian liters to us gallons" and "liters to canadian gallons" are distinct conversions. When you are unsure, convert with both factors using the table above and decide whether the difference is large enough to matter for what you are doing.

Common conversions and use cases

Many searches run the other way too — people have liters and want gallons. The reverse factor is gallons = liters × 0.264172 for US gallons. The list below covers the popular lookups in both directions.

• 1 gallon — 3.79 L (US) / 4.55 L (UK)
• 2 gallons — 7.57 L (US)
• 3 gallons — 11.36 L (US)
• 4 gallons — 15.14 L (US)
• 5 gallons — 18.93 L (US), the classic water-cooler or gas-can size
• 12 gallons — 45.42 L (US)
• 25 gallons — 94.64 L (US)
• 1 liter — 0.264 US gallons

Where it matters: comparing fuel prices and tank capacities between the US and metric countries, sizing aquariums and water tanks, mixing garden chemicals and pool treatments, and reading container labels that list one unit but not the other. If you are converting Canadian or UK figures, remember the imperial gallon is bigger, so a "liters to US gallons" result will differ from a "liters to Canadian gallons" one. Beyond volume, the Unit Converters set includes a Power converter, a Weight converter, and a Temperature converter for the other measurements that often come up in the same task.

Some concrete examples bring the scale to life. A typical car fuel tank of 12 to 16 US gallons holds about 45 to 61 liters. A standard home water-cooler bottle is 5 US gallons, or 18.93 liters. A large fish tank advertised at 55 gallons holds roughly 208 liters, which matters a great deal when you are calculating the dose of a water treatment measured per liter. Garden sprayers, pool chemicals, and brewing equipment are all sold and dosed in mixed units, so converting once and writing down the liter figure prevents repeated arithmetic and the mistakes that come with it.

Fuel pricing is the conversion people feel most directly. A price of, say, four US dollars per gallon works out to about 1.06 dollars per liter, which is how you compare it against a per-liter price abroad. Doing that comparison correctly means using the US gallon factor for US prices and the imperial factor for any older UK figures — mixing them up makes one country's fuel look far cheaper or dearer than it really is.

Common mistakes to avoid

• Mixing up US and UK gallons. The imperial gallon (4.546 L) is about 20% larger than the US gallon (3.785 L). Using the wrong one throws off fuel-economy and capacity math badly.
• Using 4 as the exact factor. Multiplying by 4 is a quick estimate, but the precise US factor is 3.78541. The difference matters for fuel and dosing.
• Dividing instead of multiplying. To go from gallons to liters you multiply by 3.78541. Dividing converts the other way by mistake.
• Comparing mpg and L/100km directly. US miles-per-gallon and metric liters-per-100km are inverse measures, so you cannot convert one to the other with the gallon factor alone.
• Forgetting the dry gallon. The US dry gallon exists too and differs from the liquid gallon. For liquids, always use the liquid gallon (3.78541 L).

Tips and related converters

Keep one anchor in mind: 1 US gallon is just under 3.8 liters, and 1 liter is about 0.26 gallons. For a fast field estimate, treat a gallon as roughly 4 liters and adjust down slightly. When accuracy counts — fuel logs, chemical mixing, billing — use the converter above with the exact 3.78541 factor and confirm whether you are working with US or imperial gallons.

For related needs, the Liters to Gallons converter handles the reverse, while the Weight converter and Temperature converter cover the other units that appear alongside volume in many tasks. You can find every measurement tool on the Unit Converters hub, all free and running in your browser with no signup.

Frequently asked questions

How many liters are in a gallon? One US liquid gallon is 3.78541 liters, and one UK (imperial) gallon is 4.54609 liters. Multiply your gallon value by the matching factor.

What is 5 gallons in liters? 5 US gallons equal about 18.93 liters. In imperial gallons it is about 22.73 liters.

What is the difference between US and UK gallons? A US gallon is 3.78541 liters while a UK gallon is 4.54609 liters, so the imperial gallon is roughly 20% larger. Match the gallon type to your source.

What is 1 gallon in liters? One US gallon is about 3.79 liters; one UK gallon is about 4.55 liters.

How do I convert liters back to gallons? Multiply the liters by 0.264172 for US gallons, or use the liters to gallons converter for an instant result.

Why does my fuel economy not convert with the gallon factor? Miles-per-gallon and liters-per-100km are inverse measures, not a simple unit swap, so converting them needs a different calculation than converting volume.

Can I just multiply by 4 for a quick estimate? Yes, for a rough figure. Multiplying US gallons by 4 slightly overestimates; use the exact 3.78541 factor when precision matters.

Do I need an account to use this converter? No. It is completely free, runs in your browser, and has no signup or usage limits.