Date & Time Duration Calculator

1. How to calculate date & time duration?
2. Time duration examples
• How long will it take?
• How much time until...
• How much time since...
• Time elapsed calculation
• How many years ago was a given year
3. Digital, analog, atomic, and Internet time

    How to calculate date & time duration?

The date and time duration calculator shows you how much time there is within a chosen period. Simply enter the starting date, starting time, end date and time, and press "Calculate". The tool will display the answer in multiple different time units at once, so you can use the one suitable for your needs. If you do not enter hours and and minutes it functions as a date duration calculator.

Keep in mind that the calculator always shows the duration in full years, months, weeks, and days between the two points in time. Hours are shown in decimal form, minutes are shown to the nearest minute. For example, if the time between two dates is 120 and a half days the result will show 120 full days. However, if the duration is 3 hours and 59 minutes, the tool will show 3.98 hours, which is 239 minutes.

    Time duration examples

We often need to deal with ages, where time differences are of interest. Say you have a friend who is about 1.5 years older than you, but you wish to know exactly how many months, weeks, and days older he is. All you need to do is enter their birth day in the upper field and enter yours in the lower field, or the other way around. Below, the duration calculator will display precisely what the difference is.

How long will it take?

Another everyday situation is in transportation, where you need to know how long it will take you to get from point A to point B on a bus, train, or in your car. Running the precise start and end time through the time difference calculator will help you plan your next trip to the store or to a business meeting downtown.

How much time until...

Yet another example of how this tool can be useful is as a "time until calculator". Say you want to start a countdown for an event scheduled to start on Feb 20, 2024 at 11:00. If today is Jul 13, 2022, 18:00 (or 6 pm). The time until the event is 5,321 full hours so the countdown should start with having that many full hours in order to have the desired time duration. In days this is 221 while there are 31 full weeks until the event.

On a smaller time frame, you might be wondering how much time you have until a meeting at 3 PM. The calculator can easily answer this and will you tell you how long until 3 PM depending on your current time. Likewise for questions like how much time till 1:45 PM or how much longer to 9 PM.

How much time since...

Date duration calculations are common when working with historical events (number of years, months, or days between events of interest), in sports (tracking progress over time), transportation, accounting, project management, and everywhere where time management is critical. E.g. it can be used to calculate the time since the start of a project or a historic battle, agreement, or the founding date of a country.

Time duration calculations can be equally important. Wondering how long has it been since you came to work today, for example how long has it been since 7:30 PM today? Or how long since 9 PM yesterday? Our tool can help with both of these by choosing the respective operating mode.

Time elapsed calculation

Time since and time elapsed are pretty much synonymous, but the first is typically used with longer time periods such as number of days since the beginning of the year, number of years since a historical event, etc. Time elapsed is more often used for shorter time periods such as the time elapsed since the start of a game of football or baseball, the start of a marathon, the beginning of an exam, and so on. There are no specifics in how these and other time and date duration calculations work.

How many years ago was a given year

On the grander scale of things, one might just care about the number of years that have passed since an event in the past. For example, how many years ago was 1980? The calculation is the same as for the age of a person or thing, a matter of simple subtraction of the year in question from the current year (2026). This gives you how many years are between them, the initial year included. For example, 1980 to 2026 is 46 years. Use our how many years calculator for these and other mathematical questions invloving calendar years.

    Digital, analog, atomic, and Internet time

Understanding different methods of timekeeping can help understand how date difference and time difference is calculated and can make it easier to use our time duration calculator.

A digital clock or watch typically displays the time in digits (through the use of the numbers 0-9). This is opposed to an analog clock which would show the passing time through moving hands. The digital clock makes it easier and quicker for most people to read the time because you simply need to look at the numbers shown rather than try and figure out where the hands of the clock are. In general, neither digital nor analog clocks are better as it always depends on the quality. The most expensive clocks in the world continue to be analog.

Radio-controlled clocks, on the other hand, get their time from the super-accurate atomic clocks. You might have heard that at a certain time some radios tell you the exact time, and this is where they get it from. To this date there is no more accurate time-keeping device than the atomic clock so if you want to know the time difference between two events with great precision, using such a clock to time the events would be preferred.

A watch or a clock does not tell you the time because it does not know it; it can only show you approximately how much time has passed since you last told it what time it is. Therefore, the watch you have in your pocket is a time-counting rather than a time-keeping device. The Radio-Controlled Clock, on the other hand, is precisely the latter, as it adjusts itself based on the radio signal it receives over and over again by the broadcaster. The date and time it shows is agreed upon worldwide (known as Coordinated Universal Time, UTC) so this is how you know that it is, in fact, the "right time" ^[1].

Internet time is a decimal time concept, introduced in 1998 by the Swiss company Swatch. Instead of the traditional hours and minutes, the Swatch Internet Time uses .beats. One .beat is equivalent to 1 min, 26.4 sec; and a mean solar day equals 1000 .beats. There are no time zones in this time concept which makes it easy to have internet appointments with people from around the globe, without having to calculate what time it is supposed to be in their country. Despite the ease in calculation, this mode of timekeeping is not very popular and thus not supported in our time duration calculator.