Write the minutes as fractions of an hour. Use the minutes as the top number or numerator of the fraction and 60 minutes (equivalent of one hour) as the bottom number or denominator. For example, 15 minutes written as a fraction of an hour is: 15/60.
Convert the fraction to a decimal number by dividing the number of minutes by 60. Fractions indicate division of the top number by the bottom number. Returning to the example of 15 minutes, 15 divided by 60 is 15/60 = 0.25.
Convert the decimal number to a percentage by moving the decimal point two places to the right and adding the percentage sign at the end. Using 0.25 as the example, it converts to 25 percent. "15" minutes converts to 25 percent of an hour.