How to use the days between dates calculator
- Days between two dates: enter a start date and an end date. You get the number of days, the same span in weeks and days, and in years, months and days.
- Add or subtract days: switch to Add or subtract days, pick a start date (today is filled in for you) and enter a number of days or weeks. The quick picks fill in 30, 60, 90, 180 or 365 days, so "90 days from today" is one click.
Results update as you type, and Copy result puts a one-line answer on your clipboard. Everything is worked out on your device.
How the days are counted
The calculator counts how many days you move forward to get from the start date to the end date. From Monday to the next Monday is 7 days. In other words, the start date is counted and the end date is not, which is the usual answer to "how many days until...".
Sometimes you want both dates counted, for example the length of a booking, a course or a leave period that includes its last day. Tick Count the end date as well and the result goes up by 1.
| From | To | Days | With end date |
|---|---|---|---|
| Jan 1, 2026 | Dec 31, 2026 | 364 | 365 |
| Oct 7, 2026 | Dec 25, 2026 | 79 | 80 |
| Feb 1, 2027 | Mar 1, 2027 | 28 | 29 |
| Feb 1, 2028 | Mar 1, 2028 | 29 | 30 |
If the end date is earlier than the start date, the calculator counts the days back and tells you so, rather than showing a negative number.
Weeks, months and years
Weeks and days is the day count divided by 7: 79 days is 11 weeks and 2 days.
Years, months and days is less simple, because months have 28 to 31 days. The calculator counts a month each time the start date's day number comes round again, then counts the days left over. From October 7, 2026 to December 25, 2026 is 2 months (to December 7) and 18 days.
When the start day does not exist in a month, the last day of that month stands in for it. From January 31, 2027 to February 28, 2027 is exactly 1 month, and to March 1, 2027 it is 1 month and 1 day. With the end date counted, a full calendar year such as January 1 to December 31, 2026 shows as exactly 1 year.
Leap years
February has 29 days in a leap year, so any span that crosses February 29 is one day longer. The calculator uses the Gregorian calendar rule, as the US Naval Observatory states it:
"Years evenly divisible by 4 are leap years, with the exception of centurial years that are not evenly divisible by 400."US Naval Observatory, Astronomical Applications
So 2028 is a leap year, 2100 is not, and 2000 was. That is why February 1 to March 1 is 28 days in 2027 but 29 days in 2028.
Adding and subtracting days
Adding days moves forward that many calendar days, weekends and holidays included. Subtracting moves back. Weeks are 7 days each. Here is what the quick picks give from Wednesday, October 7, 2026:
| From Oct 7, 2026 | Date |
|---|---|
| 30 days later | Friday, November 6, 2026 |
| 60 days later | Sunday, December 6, 2026 |
| 90 days later | Tuesday, January 5, 2027 |
| 180 days later | Monday, April 5, 2027 |
| 365 days later | Thursday, October 7, 2027 |
| 90 days earlier | Thursday, July 9, 2026 |
Notices and contracts sometimes say how to count a period, for example whether the first day counts or what happens when the last day is a weekend. If a deadline matters, follow the wording of the document. To skip weekends and public holidays, use the business days calculator.
Questions and answers
What is 90 days from today?
Open Add or subtract days, which starts from today, and press 90 days. From October 7, 2026, for example, 90 days later is Tuesday, January 5, 2027.
Does the count include the start date or the end date?
It counts the days from the start date to the end date, so Monday to the next Monday is 7 days. Tick "Count the end date as well" to include both dates, which adds 1.
How many days are there between two dates in different years?
Enter both dates and the calculator counts every day between them, including February 29 in leap years. January 1, 2026 to January 1, 2027 is 365 days.
Why does the months figure look odd near the end of a month?
Months have different lengths. A month is counted when the start day number comes round again, and the last day of a shorter month stands in for a day it does not have. So January 31 to February 28, 2027 counts as 1 month: February has no 31st, so its last day takes that place. January 31 to February 27 is 27 days.
Can a time zone or daylight saving change the answer?
No. The calculator works with calendar dates only, never clock times, so a clock change or your time zone cannot add or remove a day. Today is taken from your own device.
Sources
Checked on 7 October 2026. If a rule has changed, please tell us.