You filled a 50 liter tank and the manual lists capacity in gallons. Which gallon, though? That’s the catch nobody warns you about. A US gallon and an Imperial gallon aren’t the same size, so picking the wrong one throws your numbers off by about 20%. This converter handles both, and it shows the math as you type.
The factor itself is fixed. One US gallon holds exactly 3.78541 liters, which flips to 1 liter = 0.264172 US gallons. So 50 liters comes out to roughly 13.21 US gallons. Switch to the Imperial side and one gallon is 4.54609 liters, making 1 liter = 0.219969 Imperial gallons. Same 50 liters, but now it reads about 11 Imperial gallons. Big difference for one tank.
US gallon or Imperial gallon?
Quick rule: if you’re in the United States, it’s almost always the US gallon. The UK, plus a handful of Commonwealth countries, historically used the larger Imperial gallon. An Imperial gallon is about 20% bigger than a US one (4.546 L versus 3.785 L), which is exactly why a “gallon of gas” in London and a “gallon of gas” in Texas describe different amounts of fuel.
The converter defaults to US gallons because that’s what most people searching for this need. There’s a toggle for Imperial right next to the result. Pick the wrong one and your aquarium dosing or your fuel math will be off by a fifth, so it’s worth a half-second glance.
Where this comes up
- Fuel and fuel economy. European cars list tank size in liters; American specs use gallons. Converting helps when you’re comparing range or pricing fuel across borders.
- Aquariums. Most tank chemistry (dechlorinator, fertilizer, medication) is dosed per gallon in US product instructions, even when your tank is labeled in liters. A 200 L tank is about 52.8 US gallons, and dosing for 200 instead would massively overdose it.
- Home brewing and cooking in bulk. Recipes and equipment float between both systems constantly.
How to use it
Type a value in the liters box and the gallon result updates on the spot. No submit button, no waiting. Flip the toggle if you need Imperial instead of US. The reference table underneath lists common amounts (1, 5, 10, 20, 50, 100 liters) already worked out both ways, so for round numbers you might not even need to type anything. Everything calculates locally in your browser. Nothing you enter gets uploaded or stored.
A couple of sanity checks worth remembering: 4 liters is just over a US gallon (1.057, close enough that people round 4 L to a gallon). And 10 liters lands at 2.64 US gallons. Memorize those two and you can eyeball most conversions.
FAQ
Is 1 liter the same as a quarter gallon?
Almost, but not quite. One liter is 0.264 US gallons, which is a hair more than a quarter (0.25). Close enough for a rough mental estimate, off by about 5.7% if you need precision.
Why do US and Imperial gallons differ?
History. The US kept an older English wine gallon definition (231 cubic inches) while Britain redefined its gallon in 1824 based on ten pounds of water. The Imperial gallon ended up about 20% larger, and the two systems never reconverged.
How many liters in a US gallon?
Exactly 3.78541 liters. The Imperial gallon is 4.54609 liters. The tool uses these exact figures, not rounded approximations.
Does anything get sent to a server?
Nope. A fixed factor crunches the figure right in the page. Your numbers stay on your device, and it works offline once the page loads.
Which gallon should I pick for a recipe?
Check where the recipe is from. US sources mean US gallons; older UK cookbooks mean Imperial. When in doubt, US gallon is the safer default for modern recipes.