Formula to convert 21 liters to gallons is to multiply 21 by 0.264172 (this is the value for 1 liter to gallon).
Convert 21 Liters to Gallons results
21 x 0.264172052 = 5.5476131004
21 l = 5.55 gal
To conclude the answer for 21 liters is five point fifty five gallons