Date Difference Calculator
Find how many days are between two dates, and how that reads in years, months and days and in weeks.
Pick a start date and an end date. The result appears as soon as both are chosen.
How to Use the Date Difference Calculator
- Choose the start date and the end date.
- Read the total number of days, then the same gap as years, months and days, and as weeks and days.
- Change either date to see the result update. Reset clears both.
How the Difference Is Calculated
Total days is the exact number of days from the earlier date to the later one. The two dates are counted as calendar dates, so a time zone or a daylight saving change cannot move the answer. The days between 1 January and 2 January are 1 day.
Years, months and days follow the calendar. Count whole months forward from the earlier date, keeping the same day of the month. When the target month is shorter, the last day of that month is used, so one month after 31 January is the last day of February. The most whole months that fit before the later date are the months; the days left over are the days.
Weeks and days divide the total days by 7.
Total Days and the Calendar Breakdown
Total days is exact. The calendar breakdown depends on how long the months in between are, so "1 month" can be 28, 29, 30 or 31 days. Two gaps with the same number of days can therefore read differently in months and days.
Leap Years and Month Lengths
Leap years are handled: 29 February exists only in a leap year, which is a year divisible by 4, except a century year unless it is divisible by 400 (so 2000 and 2024 are leap years, 1900 and 2100 are not). From 29 February, one year later is 28 February in a year that is not a leap year.
Example
From 1 January 2026 to 10 February 2026 is 40 days, which the calendar counts as 1 month, 9 days (5 weeks, 5 days). A month-end start shows how the rule works: from 31 January 2026 to 1 March 2026 is 29 days, which is 1 month, 1 day, because one month after 31 January is the last day of February.
Common Uses
- How long until a deadline, or how long since a start date.
- The length of a trip, a booking period or an event.
- The span of a subscription, a contract or an employment period.
- Planning a project between two milestones.
This calculator counts every calendar day. It does not calculate business days, public holidays or working calendars, and it does not use the time of day. See the disclaimer.
Date Difference Calculator FAQ
Does it count both the start and the end date?
No. The total is the number of days between the dates: from 1 January to 2 January is 1 day. If you want to count both days, add 1.
What if the end date is before the start date?
You get the distance between them, with a note that the end date comes before the start date. Nothing is swapped silently.
Why is "1 month" sometimes 28 days and sometimes 31?
Months have different lengths. The calendar breakdown counts whole calendar months, so a month can be 28, 29, 30 or 31 days. The total number of days is always exact.
Does the time zone or daylight saving change the result?
No. The dates are treated as calendar dates with no time of day, so the result is the same anywhere.
Can it count business days or skip holidays?
No. It counts every calendar day. Business days and holidays depend on a country and a calendar, which this calculator does not use.