Each day has 24 hours, but in that time, a clock's hour hand makes two 12-hour laps. In military time, the clock is marked with a 24-hour face, and the hour hand moves from 12 noon to 13, instead of beginning a second transit toward 1:00. The time clock that your employees use to punch in is based on this "military" time. The easy ways to calculate payroll hours in military time use subtraction, addition division and multiplication.

The 24-hour Clock

The military clock makes time specific, avoiding confusion about "a.m." or "p.m." To convert 12-hour time to 24-hour time, you add 12 to the hours after noon. On the 24-hour clock, 1 p.m. is 1300 -- "thirteen hundred" -- and 2400 is midnight. The first two numbers are the hour, the second two numbers are the minutes after the hour -- 1345 is 1:45 p.m. One minute after midnight is 0001, and half-past midnight is 0030.

The 8-hour Workday

A shift that runs from 7 a.m. to 7 p.m., counted in the a.m./p.m. method, is obviously 12 hours long, On a 12-hour clock, an eight-hour shift starting at 7 a.m. ends at 3 p.m. Using the 24-hour clock, however, if the shift begins at 0700, or "zero-seven hundred," the end of the eight-hour shift is calculated by adding eight hours: Seven plus eight equals 15, or 1500.

Daily Hours Worked

If an employee's time card shows he clocked in at 0700 and clocked out for lunch at 1105, subtract 700 from 1,105. The answer, 400, is the number of hours -- four -- and minutes, five, that he worked before lunch. If he clocks in at 1200, or "twelve hundred," and works until 1600, subtract 1,200 from 1,600. The answer, 400, is how many hours -- the first number -- and minutes -- the second two numbers -- that the employee worked after lunch. Add the time worked before lunch, four hours and five minutes, to the time worked afterward, and you find that the employee worked eight hours and five minutes for the day.


At the end of the week, add up the minutes of overtime worked each day and the hours of overtime each day. If an employee worked four 12-hour days, four times 12 is 48 hours, exactly eight hours more than 40 hours. If an employee worked an additional 55 minutes one day and an additional 53 minutes another day, add 55 and 53. Divide the result, 108, by 60. Multiply the answer, 1.8, by the employee's overtime pay rate.