Formula to convert 1.5 liters to gallons is to multiply 1.5 by 0.264172 (this is the value for 1 liter to gallon).
Convert 1.5 Liters to Gallons results
1.5 x 0.264172052 = 0.3962580786
1.5 l = 0.4 gal
To conclude the answer for 1.5 liters is zero point four gallons