Hours Calculator

To calculate hours between two times, subtract the start time from the end time. First, convert both times to 24-hour format: 8:30 AM becomes 08:30 and 5:15 PM becomes 17:15. Then subtract the hours and minutes separately: 17 - 8 = 9 hours, 15 - 30 = -15 minutes. Since the minutes are negative, borrow 1 hour (making it 8 hours) and add 60 to the minutes (-15 + 60 = 45 minutes). The result is 8 hours 45 minutes. For overnight calculations where the end time is earlier than the start time, add 24 hours to the end time before subtracting. For example, from 10:00 PM (22:00) to 6:00 AM (06:00), calculate as (06:00 + 24:00) - 22:00 = 30:00 - 22:00 = 8 hours.

To add hours and minutes, handle each unit separately and carry over when minutes exceed 60. For example, to add 3 hours 45 minutes and 2 hours 30 minutes: first add the minutes (45 + 30 = 75), then convert excess minutes to hours (75 minutes = 1 hour 15 minutes), and finally add all hours (3 + 2 + 1 = 6 hours). The total is 6 hours 15 minutes. The same principle applies to subtraction but in reverse — if you need to subtract more minutes than available, borrow 1 hour (which equals 60 minutes) from the hours column. For chaining multiple time additions, it's often easiest to convert everything to total minutes first, add them up, then convert back to hours and minutes at the end.

Decimal hours express time as a decimal number rather than hours and minutes. For example, 2 hours 30 minutes equals 2.50 decimal hours, and 7 hours 45 minutes equals 7.75 decimal hours. To convert, divide the minutes by 60 and add to the hours: 45 / 60 = 0.75, so 7:45 = 7.75. Decimal hours are widely used because they simplify payroll calculations, billing, and mathematical operations. Multiplying a decimal hour value by an hourly rate gives you an exact dollar amount without the extra step of converting minutes to fractions of an hour. Most payroll software, accounting systems, billing platforms, and project management tools use decimal hours as their standard input format. Common conversions to remember: 15 min = 0.25, 30 min = 0.50, 45 min = 0.75, 6 min = 0.10, and 12 min = 0.20.

To calculate net work hours with breaks, first find the total elapsed time (end time minus start time), then subtract all break periods. For example, if you clock in at 8:00 AM and clock out at 5:00 PM with a 30-minute lunch and two 15-minute rest breaks, the gross time is 9 hours and total break time is 60 minutes (30 + 15 + 15). Net work hours are 9 hours minus 1 hour = 8 hours. Federal law (FLSA) does not mandate rest or meal breaks for adult workers, but when employers do provide short breaks of 5-20 minutes, that time is generally considered compensable work time. Meal breaks of 30 minutes or longer can be unpaid only if the employee is completely relieved of duties. Many states have their own break requirements — for example, California requires a 30-minute unpaid meal break for shifts over 5 hours and a second meal break for shifts over 10 hours.

To convert minutes to decimal hours, divide the number of minutes by 60. For example: 15 minutes / 60 = 0.25 hours, 20 minutes / 60 = 0.33 hours, 30 minutes / 60 = 0.50 hours, and 45 minutes / 60 = 0.75 hours. For a combined hours-and-minutes value, keep the hours as-is and convert only the minutes: 6 hours 20 minutes = 6 + (20/60) = 6.333 hours. To convert back from decimal to minutes, multiply the decimal portion by 60: 0.333 x 60 = 20 minutes. When precision matters for payroll, round decimal hours to two decimal places, which gives you accuracy to about 36 seconds. Most payroll systems accept two decimal places as standard. A quick reference chart: 5 min = 0.08, 10 min = 0.17, 15 min = 0.25, 20 min = 0.33, 25 min = 0.42, 30 min = 0.50, 35 min = 0.58, 40 min = 0.67, 45 min = 0.75, 50 min = 0.83, 55 min = 0.92.

Our base-60 time system traces back to the ancient Sumerians and Babylonians (circa 3000 BCE), who developed sexagesimal (base-60) mathematics. They chose 60 because it has an unusually large number of divisors — 60 is evenly divisible by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, and 60. This makes it exceptionally easy to divide an hour into halves, thirds, quarters, fifths, sixths, and twelfths without producing repeating decimals. The ancient Egyptians divided daylight and nighttime into 12 segments each (giving us 24 hours), and the Greeks further refined the system by dividing degrees into 60 minutes and minutes into 60 seconds — a convention later applied to timekeeping. While base-10 time systems have been proposed (notably during the French Revolution, which briefly introduced a 10-hour day with 100 minutes per hour), none have gained widespread adoption because the base-60 system is so deeply embedded in culture, technology, and infrastructure.

When calculating time across midnight, the end time appears smaller than the start time because the clock resets at 12:00 AM (00:00). The solution is to add 24 hours to the end time before subtracting. For example, for a shift from 10:00 PM to 6:30 AM: convert to 24-hour format (22:00 to 06:30), add 24 to the end time (06:30 becomes 30:30), then subtract (30:30 - 22:00 = 8 hours 30 minutes). Alternatively, you can split the calculation at midnight: time from 22:00 to midnight (24:00) = 2 hours, time from midnight (00:00) to 06:30 = 6 hours 30 minutes, total = 8 hours 30 minutes. Our calculator automatically detects when the end time is earlier than the start time and applies the midnight-crossing adjustment, so you don't need to perform these steps manually.

For payroll, you need to convert raw clock times into compensable hours using these steps: First, record clock-in and clock-out times for each work period. Second, calculate gross hours by subtracting clock-in from clock-out. Third, deduct any unpaid break periods (typically meal breaks of 30+ minutes). Fourth, convert the net hours to decimal format for payroll software. Fifth, total all daily hours across the workweek. Sixth, separate regular hours (first 40) from overtime hours (beyond 40) for non-exempt employees. For example: an employee clocks in at 7:58 AM and out at 5:03 PM with a 30-minute unpaid lunch. With 15-minute rounding, 7:58 rounds to 8:00 and 5:03 rounds to 5:00. Gross time is 9 hours, minus 30 minutes for lunch equals 8.50 decimal hours of compensable time. Repeat this for each day, total the week, and apply overtime rules as required.

The 7-minute rule is the most common payroll rounding practice in the United States. Under this system, time is rounded to the nearest 15-minute increment, with 7 minutes being the midpoint. Times of 1-7 minutes past the quarter hour round down, and times of 8-14 minutes round up. For example: a clock-in at 8:07 rounds down to 8:00, while 8:08 rounds up to 8:15. Similarly, a clock-out at 5:22 rounds down to 5:15, while 5:23 rounds up to 5:30. The U.S. Department of Labor permits this rounding under 29 CFR 785.48, provided it averages out fairly over time and does not consistently favor the employer. Some organizations use 5-minute or 6-minute rounding increments instead. It's important to note that the rounding policy must be applied uniformly to all non-exempt employees and cannot be used selectively to reduce payable hours.

The Fair Labor Standards Act (FLSA) defines overtime as any hours worked beyond 40 in a single workweek for non-exempt employees. The workweek is defined as any fixed, recurring period of 168 consecutive hours (7 days x 24 hours), and the employer chooses when it begins. Overtime must be compensated at a minimum rate of one and one-half times (1.5x) the employee's regular rate of pay. Importantly, FLSA overtime is calculated on a workweek basis only — there is no federal requirement for daily overtime. An employee who works 12 hours on Monday and 4 hours on Tuesday is not owed overtime unless the weekly total exceeds 40 hours. However, some states (notably California) do require daily overtime after 8 hours. Exempt employees (salaried workers meeting specific duties and salary tests) are not covered by FLSA overtime provisions. As of 2024, the salary threshold for exemption is $684 per week ($35,568 annually), though this amount is subject to periodic updates by the Department of Labor.