Dates & Time

Date Calculator (Difference & Add/Subtract)

Find the days between two dates, add or subtract days from a date, or show today with its weekday, ISO date, and Julian Day Number.

How to use
  1. Pick a mode: days between dates, or add/subtract days.
  2. Enter your start date and, depending on mode, an end date or a day count.
  3. Switch to the today view for the current Julian Day Number.
Date math uses your inputs as given; check time-zone and leap-year edge cases.
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Common questions

How do I count the number of days between two dates?

Enter both dates and the calculator subtracts them, counting whole days between them and handling leap years automatically.

What is a Julian Day Number?

It is a continuous count of days used in astronomy, starting from a fixed point in 4713 BC, which makes date math across calendars simple.

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