Formula to convert 15 liters to gallons is to multiply 15 by 0.264172 (this is the value for 1 liter to gallon).
Convert 15 Liters to Gallons results
15 x 0.264172052 = 3.962580786
15 l = 3.96 gal
To conclude the answer for 15 liters is three point ninety six gallons