Formula to convert 81 liters to gallons is to multiply 81 by 0.264172 (this is the value for 1 liter to gallon).
Convert 81 Liters to Gallons results
81 x 0.264172052 = 21.3979362444
81 l = 21.4 gal
To conclude the answer for 81 liters is twenty one point four gallons