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Gallons (US) measure larger liquid volumes in the imperial system; litres in the metric one. Fuel, water use and container sizes cross between them, so this converter turns US gallons into litres and back.
Gallons to Liters Converter: step-by-step worked example
How many litres does a 15-gallon fuel tank hold?
- Value
- 15
- Direction
- US gallons → Litres
- 1
Conversion factor (definition)
1 US gallon = 231 in³ = 3.785411784 L (exact)
1 gal = 3.785411784 L = 3.7854 L
- 2
Inverse factor
1 L = 1 ÷ 3.785411784 gal
1 ÷ 3.785411784 = 0.2642 gal
- 3
Conversion
gal → L: × 3.785411784 · L → gal: ÷ 3.785411784
15 gal × 3.785411784 = 56.7812 L
- 4
Check (reverse direction)
Convert the result back with the inverse operation
56.7812 L ÷ 3.785411784 = 15 gal
- US gal15
- L56.7812
- UK gal12.4901
- qt60
Good to know: The imperial (UK) gallon is 4.54609 L — about 20% larger than the US gallon. Check which gallon your source uses.
Gallons to Liters Converter — how it works
The conversion factor
1 US gallon = 3.785412 litres.
| To convert | Do this |
|---|---|
| gal → L | multiply by 3.785412 |
| L → gal | divide by 3.785412 |
This is the US gallon. The UK (imperial) gallon is larger at 4.546 litres.
Common values
| US gallons | Litres |
|---|---|
| 1 gal | 3.79 L |
| 5 gal | 18.93 L |
| 10 gal | 37.85 L |
| 15 gal | 56.78 L |
Worked example
A 15-gallon fuel tank holds 15 × 3.785412 = 56.8 litres. A 5-gallon water bottle is 18.9 L. To go back, 40 L of fuel is 40 ÷ 3.785412 = 10.57 US gallons.
Gallons to litres table
| Gallons (US) | Litres |
|---|---|
| 1 | 3.79 |
| 2 | 7.57 |
| 3 | 11.36 |
| 5 | 18.93 |
| 10 | 37.85 |
| 15 | 56.78 |
| 20 | 75.71 |
| 50 | 189.27 |
Litres to gallons table
| Litres | Gallons (US) |
|---|---|
| 1 | 0.26 |
| 5 | 1.32 |
| 10 | 2.64 |
| 20 | 5.28 |
| 40 | 10.57 |
| 50 | 13.21 |
| 60 | 15.85 |
| 100 | 26.42 |
Frequently asked questions
How many litres is 1 US gallon?+
One US gallon is 3.785412 litres. Multiply gallons by 3.785412 to get litres.
How do I convert gallons to litres?+
Multiply the gallon value by 3.785412. For example, a 20-gallon tank is 20 × 3.785412 = 75.7 L.
Is this a US or UK gallon?+
This uses the US gallon (3.785 L). The imperial (UK) gallon is noticeably larger at 4.546 litres — about 20% more — so the distinction matters for fuel economy figures.
How do I convert litres back to gallons?+
Divide the litre value by 3.785412. So 50 L is 50 ÷ 3.785412 = 13.2 US gallons.
How many litres in 5 gallons?+
5 US gallons is 18.93 litres — the size of a typical large water-cooler bottle.
About this page
- Publisher:
- Kalkoro — Teknolojig Bilişim Teknolojileri A.Ş., İstanbul
- Written by:
- Ahmet Tur — Editor (Math, date & time, unit conversion, physics & chemistry, everyday tools)
- Reviewed by:
- Kübra Yıldız — Editor
Parameters come from official sources; the last update date is shown at the bottom of the page.
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How we calculate and our accuracy policy →
Results are for information only. For official matters the relevant authority's calculation prevails.
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