Formula to convert 15.5 liters to gallons is to multiply 15.5 by 0.264172 (this is the value for 1 liter to gallon).
Convert 15.5 Liters to Gallons results
15.5 x 0.264172052 = 4.0946668122
15.5 l = 4.09 gal
To conclude the answer for 15.5 liters is four point zero nine gallons