Time Calculator
Calculate dates, elapsed time and durations
Calculate elapsed time, find a date before or after another date, and express the same duration in different units.
Key idea
A calendar unit and a fixed duration answer different questions. Months have different lengths, and leap years change the calendar. Adding one month is therefore not the same operation as adding a universal number of days.
Try this first
Choose two dates and compare the elapsed duration in days and hours. Then start from one date and add a calendar month. Compare that result with adding a fixed number of days to see why calendar units and fixed durations are different.
How to get started
- Choose Duration for the time between dates, Projection to add or subtract time, or Converter to change time units.
- Enter both dates, or enter a starting date and the years, months, days or hours to apply.
- Calculate and compare the result in the displayed units. Calendar months and years depend on the dates involved.
Explore a little further
Try another experiment
Compare the interval from February 1 to March 1 in a leap year and a non-leap year. Then compare both with adding a fixed duration of 28 days. State whether you are measuring elapsed time or moving through the calendar.
Good to know
Months and years do not all have the same duration. Check the selected dates and units before using a result; the tool does not establish legal deadlines or the timing rules of another service.
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