Date Difference Calculator
Date Difference Calculator is a free time tool that runs directly in your browser with no account required.
About this tool
This calculator counts the days between any two calendar dates, whether you are measuring a project timeline, an invoice term, or time until a deadline. It reports the gap in whole days and in weeks, and tells you whether the end date is ahead of or behind the start. Both dates are treated as calendar dates, so the count is exact regardless of daylight saving changes.
How to use
- Pick the earlier date in Start date.
- Pick the later date in End date.
- Read the Days and Weeks values; the Direction row shows Forward when the end date is after the start, or Backward if you reversed them.
Frequently asked questions
How is the day count computed?
Both dates are interpreted at midnight UTC and the difference is divided by 86,400,000 milliseconds per day. Because both endpoints use the same fixed reference, the result is always a whole number of calendar days.
Is the count inclusive or exclusive?
It is exclusive of the start date: January 1 to January 2 counts as 1 day. If you need an inclusive count, such as nights plus checkout day, add 1 to the result.
Does daylight saving time affect the result?
No. Dates are compared at UTC midnight rather than local clock time, so DST transitions in your timezone never add or drop a day.
What does a negative or Backward result mean?
It means your end date is earlier than your start date. The Days value goes negative and Direction shows Backward; swap the two dates to get a positive count.
How is the Weeks figure calculated?
It is simply the day count divided by 7, shown to two decimal places, so 10 days displays as 1.43 weeks.