US Gallons to Liters Converter
Convert US gallons to liters for American liquid measurement.
How It Works
Formula: US gal to L = value × 3.785411784
Example: 1 US gal = 3.785412 L
Note: 1 US gallon equals 3.785411784 liters using the US customary liquid gallon standard, based on 231 cubic inches.
Common Uses
Quick Conversion Table
| US gal | L |
|---|---|
| 0.5 | 1.8927 |
| 1 | 3.7854 |
| 2 | 7.5708 |
| 4 | 15.1416 |
| 8 | 30.2833 |
| 16 | 60.5666 |
| 32 | 121.1332 |
| 64 | 242.2664 |
Rounding Rule
Rounded to 6 decimal places
Error Margin
±0.00001 L
Precision Guidance
For everyday use, 2-3 decimal places is sufficient. For industrial or scientific use, maintain full precision.
Common Mistakes
Do not confuse US gallon with imperial gallon. This converter uses the US customary liquid gallon (3.785411784 L), not the imperial gallon (4.54609 L).
Frequently Asked Questions
What is 1 US gallon in liters?
1 US gallon equals exactly 3.785411784 liters using the US customary liquid gallon standard.
Is US gallon different from imperial gallon?
Yes, the US gallon (3.785 L) is smaller than the British imperial gallon (4.546 L). This converter uses the US customary gallon only.
Why are there different gallon standards?
The US and UK historically used different gallon definitions. The US liquid gallon is based on the wine gallon (231 cubic inches), while the imperial gallon is larger.
How to use this converter for fuel consumption?
For MPG to L/100km conversion or liquid measurements, this converter provides the accurate US gallon to liter conversion needed for American fuel economy calculations.
Deep Dive Guide
Gallons to Liters: Convert US Volume to Metric Units
Convert gallons to liters with the exact US formula (multiply by 3.78541). Covers fuel, paint, and water for recipes, travel, and import labels.
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Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 US gallon (gal) = 3.785411784 litres (exact, 231 in³)
- EXACT1 US fluid ounce (fl oz) = 29.5735295625 mL (exact, 1/128 gal)
- EXACT1 US cup = 236.5882365 mL (exact, 8 fl oz)
- EXACT1 US pint (pt) = 473.176473 mL (exact, 16 fl oz)
- EXACT1 US quart (qt) = 946.352946 mL (exact, 32 fl oz)
- EXACT1 litre (L) = 1000 millilitres (definition)
Common Pitfalls & How to Avoid Them
US vs. Imperial (UK) cups
A US cup is 236.59 mL, but a UK/metric cup is 250 mL and an Imperial cup is ~284 mL. Recipes from different countries are not interchangeable drop-in.
Fluid ounce is volume, not mass
A US fl oz is 29.57 mL of volume. 1 fl oz of water ≈ 29.57 g, but 1 fl oz of honey or oil weighs more. Do not treat fluid ounces as grams.
Teaspoon/tablespoon sizes differ
1 US tbsp = 14.7868 mL; 1 US tsp = 4.92892 mL. Metric measuring spoons are 15 mL and 5 mL — close but not exact; for baking precision use weighed grams.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
- BIPM (International Bureau of Weights and Measures) — SI Brochure — The International System of Units (9th edition)
Last Updated 2026 | This converter was reviewed for accuracy