Quick Answer: Gallons (US) to Liters
One US gallon is approximately 3.785 liters (1 gal ≈ 3.785 L).
Conversely, 1 L ≈ 0.2642 gal.
Formula: L = gal × 3.785411784
Worked examples
- 1 gal ≈ 3.785 L
- 2 gal ≈ 7.571 L
- 5 gal ≈ 18.93 L
Method and limitations
Multiply US gallons by 3.785411784. The US liquid gallon is exactly 231 cubic inches = 3.785411784 L. The imperial gallon is a different unit: exactly 4.54609 L, about 20% larger. Calculations use full-precision constants; answers in this box are rounded for readability (≈ marks a rounded value) and the calculator shows up to 9 significant figures. This page uses the US customary liquid gallon (3.785411784 L). The imperial gallon is 4.54609 L, about 20% larger.
Each factor is exact by definition, derived from exact definitions, or a documented conventional value — see the methodology and sources.
Conversion Formula
Multiply US gallons by 3.785411784. The US liquid gallon is exactly 231 cubic inches = 3.785411784 L. The imperial gallon is a different unit: exactly 4.54609 L, about 20% larger.
Complete Guide to Gallons (US) to Liters Conversion
What is a US gallon?
The US liquid gallon (gal) equals 4 US quarts or 128 US fluid ounces. The US liquid gallon is exactly 231 cubic inches = 3.785411784 L. It is not the US dry gallon or the imperial gallon.
What is a liter?
The liter (L) is 1 cubic decimeter (1,000 cm³), a non-SI unit accepted for use with the SI.
How the Conversion Works
L = US gal × 3.785411784. The factor is exact, derived from 231 in³ and the exact inch.
Step-by-Step Conversion Guide
Follow these steps to convert gallons (us) to liters manually:
Start with your value in gallons (us)
Example: You want to convert 5 gal
Apply the conversion formula
Use the formula: L = gal × 3.785411784
Calculate the result
5 gal = 18.9271 L
Verify your answer
Use our calculator above to double-check your manual calculation.
Quick Mental Math Tip
Multiply by 4 and take off 5%: 10 US gal ≈ 40 − 2 = 38 L (exact 37.85).
Common Conversions
| Gallons (US) (gal) | Liters (L) | Liters → Gallons (US) |
|---|---|---|
| 1 gal | 3.78541 | 1 L = 0.264172 gal |
| 2 gal | 7.57082 | 2 L = 0.528344 gal |
| 5 gal | 18.9271 | 5 L = 1.32086 gal |
| 10 gal | 37.8541 | 10 L = 2.64172 gal |
| 15 gal | 56.7812 | 15 L = 3.96258 gal |
| 20 gal | 75.7082 | 20 L = 5.28344 gal |
| 50 gal | 189.271 | 50 L = 13.2086 gal |
| 100 gal | 378.541 | 100 L = 26.4172 gal |
| 500 gal | 1,892.71 | 500 L = 132.086 gal |
| 1000 gal | 3,785.41 | 1000 L = 264.172 gal |
Popular Gallons (US) to Liters Conversions
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When You'll Need This Conversion
US fuel and tank sizes
Read a US vehicle tank or fuel quantity in liters.
US containers
A 5 US gal bucket holds 18.93 L.
Common Mistakes to Avoid
Using the US factor on imperial gallons
UK fuel economy and older UK volumes use the imperial gallon.
Imperial: × 4.54609. US: × 3.785411784.
Frequently Asked Questions
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Conversion factors on this page are either exact by definition, derived from exact definitions, or conventional values in documented use. Each is listed with its source in our conversion methodology and sources, which cites the BIPM SI Brochure, NIST Special Publication 811 and the relevant IEC or national standards. Results are rounded for display only; calculations use full precision.