Free Gallons (US) to Liters Converter
The US gallon is 3.785411784 liters. This converter is essential for fuel economy, aquarium sizing, and understanding water consumption across metric and imperial systems.
Pick any units and edit either box — it converts instantly in your browser.
Quick answer
One US gallon equals 3.785 liters. To convert, multiply your gallon value by 3.785. This differs from the UK imperial gallon, which is 4.546 liters.
Formula & method
liters = gallons (us) × 3.785411784
- gal — value in gallons (us)
- L — result in liters
- 3.785411784 — exact conversion factor (1 gal = 3.785411784 L)
To convert back, divide by 3.785411784 (1 L = 0.264172 gal).
Gallons (US) to Liters — common values
| Gallons (US) (gal) | Liters (L) |
|---|---|
| 1 gal | 3.7854 L |
| 2 gal | 7.5708 L |
| 3 gal | 11.3562 L |
| 5 gal | 18.9271 L |
| 10 gal | 37.8541 L |
| 15 gal | 56.7812 L |
| 20 gal | 75.7082 L |
| 50 gal | 189.2706 L |
Examples
- Input
- 1 gal
- Result
- 3.7854 L
- Why
- Typical 1-gallon starter tank for a single fish
- Input
- 10 gal
- Result
- 37.8541 L
- Why
- Common amount at a pump during city driving
- Input
- 50 gal
- Result
- 189.2706 L
- Why
- Typical capacity for RV or emergency water storage
- Input
- 20 gal
- Result
- 75.7082 L
- Why
- Portable kiddie pool or inflatable tub capacity
Common mistakes
- Mixing up unit definitions — Uses the US liquid gallon (3.785 L), not the imperial gallon (4.546 L).
- Rounding too early. Multiply by the full factor (3.785411784) first, then round only the final liters value.
- Converting the wrong way. This page goes Gallons (US) → Liters; to go back, divide by 3.785411784.
Frequently asked questions
Is the US gallon the same as the UK (imperial) gallon?
No. The US liquid gallon is 3.785 liters, while the UK imperial gallon is 4.546 liters. This converter uses the US gallon, which is what gasoline pumps and most product labels show in the US.
Why do fuel economy calculations use gallons?
In the US, fuel tank capacity and consumption (miles per gallon) are measured in gallons, making it essential to convert to liters when comparing efficiency with metric countries or international vehicles.
How many liters is a typical car fuel tank?
A typical US car holds 12–16 gallons, which is roughly 45–60 liters. SUVs and trucks often hold 20–30 gallons (75–115 liters).
Can I use this to calculate aquarium water volume?
Yes. If you have a tank rated in gallons, multiply by 3.785 to get the exact liter capacity needed for equipment sizing or water treatment dosing.
What's the rounding issue with US gallons?
The exact US gallon is 3.785411784 liters, but in practice 3.785 is rounded enough for most purposes. Our converter keeps 4 decimal places for precision.
Why do I see different gallon values online?
Some sources use 3.78 or 3.8 for simplicity, but the legal US gallon is exactly 3.785411784 liters. Always check the source when precision matters.
Sources & references
External references open in a new tab. We are independent and not affiliated with these organizations.
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- ✓ Formula and method shown above
Provided “as is” for general information only — results may be inaccurate, so verify before you rely on them. No warranty; use at your own risk.
Built and reviewed by HIFreeTools against the formula shown above and any authoritative references cited on this page. See our methodology and editorial standards.
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