Hours Calculator

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Use the calculators below to find the number of hours and minutes between two times. For a full time card, please use the Time Card Calculator.

Start Time:	AM PM Now
End Time:	AM PM Now

Hours Between Two Dates

Start Time:	AM PM Now
End Time:	AM PM Now

RelatedTime Card Calculator | Time Calculator

An hour is most commonly defined as a period of time equal to 60 minutes, where a minute is equal to 60 seconds, and a second has a rigorous scientific definition. There are also 24 hours in a day. Most people read time using either a 12-hour clock or a 24-hour clock.

12-hour clock:

A 12-hour clock uses the numbers 1-12. Depending on the clock being used, most analog clocks or watches may not include an indication of whether the time is in the morning or evening. On digital clocks and watches, "AM" stands for ante meridiem, meaning "before midday," while "PM" stands for post meridiem, or "after noon." By convention, 12 AM denotes midnight, while 12 PM denotes noon. Using the terms "12 midnight" and "12 noon" can remove ambiguity in cases where a person may not be accustomed to conventions.

24-hour clock:

A 24-hour clock typically uses the numbers 0-23, where 00:00 indicates midnight, and a day runs from midnight to midnight over the course of 24 hours. This time format is an international standard, and is often used to avoid the ambiguity resulting from the use of a 12-hour clock. The hours from 0-11 denote what would be the AM hours on a 12-hour clock, while hours 12-23 denote the PM hours of a 12-hour clock. In certain countries, 24-hour time is referred to as military time, since this is the time format used by militaries (and other entities) around the world, where unambiguous time measurement is particularly important.

Hours in different time periods

Description	Hours
Hours in a day	24
Hours in a week	168
Hours in a month	672 for a 28-day month696 for a 29-day month720 for a 30-day month744 for a 31-day month730.5 on average
Hours in a year	8,760 for a 365-day year8,784 for a 366-day year8,766 on average
Hours in a decade	87,648 for a 2-leap-year decade87,672 for a 3-leap-year decade87,660 on average
Hours in a century	876,600