Gallons ↔ Liters Converter
Convert between US gallons, Imperial gallons, and liters for fuel planning. Note: US gallons and Imperial gallons are NOT the same — 1 Imperial gallon is about 20% larger than 1 US gallon.
Formula
1 US gal = 3.78541 L 1 Imp gal = 4.54609 L 1 US gal = 0.8327 Imp gal
US gallons are used in American aviation. Imperial gallons are used in some Commonwealth countries. Always verify which gallon type is referenced in your POH.
Reference Table
| US Gal | Imp Gal | Liters | Context |
|---|---|---|---|
| 10 | 8.3 | 37.9 | Small reserve quantity |
| 40 | 33.3 | 151.4 | Typical C172 usable fuel |
| 56 | 46.6 | 212.0 | C172SP total fuel capacity |
| 84 | 69.9 | 318.0 | C182 total fuel capacity |
| 100 | 83.3 | 378.5 | Round reference number |
Aviation Context
100LL avgas weighs 6.0 lbs per US gallon. Jet-A weighs 6.7 lbs per US gallon. Confusing US and Imperial gallons when fueling can lead to dangerous fuel shortages. The Gimli Glider incident (1983) was caused in part by a metric/imperial fuel calculation error.
Why This Matters in Aviation
Fuel is bought by volume but flown by weight, and unit confusion has caused real emergencies. US aviation uses US gallons, but Imperial gallons (about 20 percent larger) and liters appear on international fuel receipts and in some aircraft documents. If a pilot orders fuel in the wrong unit or mixes US and Imperial gallons during planning, the aircraft can depart with far less fuel than intended. The 1983 Gimli Glider incident, in which a Boeing 767 ran out of fuel, involved exactly this kind of metric/imperial calculation error, which is why cross-checking fuel units and weights is a core airmanship habit.
Understanding This Conversion
Fuel quantity crosses unit systems constantly in aviation: United States gallons are standard at American fields, while liters are the norm across most of the world, and Imperial gallons still appear in some places. Because fuel is the resource that most directly limits a flight, a conversion error can translate into carrying far less fuel than intended. This converter keeps gallons and liters aligned so your fuel plan survives a stop at an unfamiliar field.
Beyond volume, fuel planning also involves weight, and the two are linked by fuel density. Understanding how gallons and liters relate, and how each converts to pounds or kilograms, gives a pilot the complete picture needed for both range and weight-and-balance planning.
Why the Unit Matters in Aviation
In the United States, fuel is sold and measured in US gallons, and aircraft fuel capacities in American documentation are given in US gallons. Most of the world dispenses aviation fuel in liters, so a pilot buying fuel abroad must convert the liter quantity back to gallons to compare against the aircraft's gallon-based capacity and burn rate. One US gallon is about 3.785 liters.
The distinction between US and Imperial gallons is an additional trap, since an Imperial gallon is about 1.2 US gallons. A fuel order or a chart that assumes Imperial gallons will not match a US-gallon expectation, so confirming which gallon is meant, and converting through liters when in doubt, prevents a shortfall. Because fuel planning drives range and reserves, these conversions are safety-critical rather than merely convenient.
Common Conversion Mistakes to Avoid
The costliest mistake is confusing US gallons with Imperial gallons, which understates or overstates the fuel by about 20 percent. When operating where Imperial gallons may be used, converting through liters removes the ambiguity.
Another error is forgetting that fuel volume changes slightly with temperature while weight does not. For weight-and-balance work, convert volume to weight using fuel density rather than assuming a fixed relationship, since a cold, dense load of fuel weighs more per gallon than a warm one.
Quick-Reference Scenarios
Buying fuel abroad
A foreign field pumps 150 liters into your tanks. Converting to about 40 US gallons lets you confirm the quantity against your aircraft's capacity and recompute your range for the next leg.
Checking a fuel order
A fuel truck offers to top off in Imperial gallons. Converting through liters to US gallons ensures the amount you receive matches what your planning assumed.
Linking volume to weight
You load 50 US gallons of avgas. At about 6 pounds per gallon that is roughly 300 pounds, a figure you carry straight into the weight-and-balance calculation.
Related Standards & Regulations
One US gallon equals exactly 3.785411784 liters, and one Imperial gallon equals about 4.546 liters, so the two gallons differ by roughly 20 percent. Using the exact factor avoids compounding small errors across a multi-leg trip.
Aviation gasoline weighs approximately 6 pounds per US gallon and jet fuel slightly more, the standard planning figures used to convert a fuel load into a weight for balance calculations. Actual density varies with temperature and fuel grade.
Related Reading & Tools
Frequently Asked Questions
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