Hours Calculator | 12 and 24 hours

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Work Time Calculator

Start Time

Hour

Min

AM/PM

End Time

Hour

Min

AM/PM

Deduct Break (Minutes)

The hour calculator helps you calculate total hours between any start time and end time. You can choose a 12-hour or 24-hour format and optionally deduct breaks to calculate the exact time you worked. This calculator is ideal for tracking work hours, shifts, and time duration.

12-Hour clock format

The 12-hour clock format is the most commonly used format in day-to-day life. This format divides the 24 hours into two 12-hour periods: AM (Ante Meridiem) - From 12:00 midnight to 11:59 in the morning. PM (Post Meridiem) - From 12:00 noon to 11:59 at night. When using this system, time is written using numbers from 1 to 12 with AM for morning and PM for afternoon and evening.

24-Hour clock format

The 24-hour clock, also commonly known as military time, is a time format used majorly in military, aviation, and railways across many countries. This format eliminates the need for AM/PM designations and avoids confusion. In this format, the day starts at midnight (00:00) and ends at 11:59 PM (23:59).

Day	Start	End	Break	Total
Monday	09:00	17:00	30m	7.5h
Tuesday	09:00	17:00	30m	7.5h
Wednesday	09:00	17:00	30m	7.5h
Thursday	09:00	17:00	30m	7.5h
Friday	09:00	17:00	30m	7.5h
Weekly Total:				37.5h

Table 1 shows the most common work start and end times with breaks.

How to input the time

The hours calculator uses time as a whole number in this calculator. E.g., 1215 for 12.15 and 142 for 1.42. Don’t use . or ;. If you enter just a number from 1 to 12, it will be considered a whole hour. When using the 12-clock format, 12 PM is noon, and 12 AM is midnight.

How to Calculate Hours

The simple formula for calculating hours is

Total Time = End Time - Start Time - Break Duration

Start Time: This is the time you start working or when the work time starts.

End Time: This is when you finished working or when the time period ended.

Break Duration: The total time (in minutes) you spent on breaks, lunches, or any non-working periods.

You can input your time in either 12-hour or 24-hour format...

Example for 12-Hour Format: Start Time: 9:00 AM, End Time: 5:00 PM, Break: 30 minutes: 8 hours - 30 mins = 7 hours 30 minutes

Example for 24-Hour Format: Start Time: 21:30, End Time: 02:00, Break: 15 minutes: (2:00 + 24:00) - 21:30 = 4 hours 30 minutes - 15m break = 4h 15m

Start	End	Break	Worked	Notes
9:00 AM	5:00 PM	60 mins	7 hours	Standard shift
8:30 AM	4:30 PM	30 mins	7.5 hours	Early start
10:00 AM	6:00 PM	45 mins	7.25 hours	Later shift
2:00 PM	10:00 PM	30 mins	7.5 hours	Evening shift
11:00 PM	7:00 AM	30 mins	7.5 hours	Overnight shift
7:00 AM	3:30 PM	15 mins	8.25 hours	Longer shift

Table 2 shows the most common work start and end times, along with break durations and corresponding shift types.

Time to decimal hours

When converting time to decimal hours, break it down into hours and minutes. For example, 9:30. The hour part remains unchanged. To convert 30 minutes to hours, 30 minutes × (1 hour / 60 minutes) = 30/60 hours = 0.5 hours. So 9:30 is equal to 9.5 hours.

To convert decimal hours into standard time. For instance, if you have 8.75 as a decimal hour. 8 hours will be untouched. To convert minutes, multiply 0.75 by 60 to get minutes – 0.75 × 60 = 45 minutes. So, 8.75 hours = 8 hours 45 minutes (8:45).