Date Difference Calculator
Count the exact days, weeks, months and years between two dates, with leap years handled.
About the Date Difference Calculator
The calculator counts calendar days using the Gregorian calendar, so leap days are included. By convention the end date isn't counted (Monday to Tuesday is 1 day); switch on “include the end date” to count both, as you would for a hotel stay counted in days or a leave request.
The formula
Days = end date − start date (+1 to include the end date)
- Months
- whole calendar months, then the remaining days
Worked example
Example: Days between = 73
- Inputs: Start date: 1 January 2026; End date: 15 March 2026; Include the end date: No.
- Formula: Days = end date − start date (+1 to include the end date)
- Result: Days between = 73
- Years, months, days: 2 months, 14 days
- Weeks: 10 weeks 3 days
- Months (approx.): 2.4
Questions people ask
How many days until a date?
Set the start date to today and the end date to the event.
Why do month counts differ online?
Months vary in length; this counts whole calendar months first, then leftover days.