Date Calculator
Count the days, weeks and weekdays between two dates, or add and subtract days, weeks, months and years.
Your dates
Counts both the first and the last day, adding 1 to the total.
Results update as you type.
Result
Enter your measurements
Choose a start date and an end date.
How the date calculator works
To count the days between two dates, the calculator turns each date into a day number and subtracts one from the other. That avoids counting month by month and handles leap years automatically. The same total is also shown in weeks, in years, months and days, and as the number of weekdays and weekend days.
To add or subtract time, it moves the date by whole calendar months first (a year is 12 months), then by the weeks and days.
Worked examples
Days until a date
From Monday, November 9, 2026 to Friday, December 25, 2026 is 46 days (the 21 days left in November plus 25 in December), or 6 weeks and 4 days. Of those, 34 are weekdays.
A deadline 90 days away
November 9, 2026 plus 90 days is Sunday, February 7, 2027: 21 days to the end of November, 31 in December, 31 in January and 7 in February.
The end of a short month
January 31, 2026 plus 1 month is February 28, 2026, because 2026 is not a leap year.
Assumptions and limitations
- Dates use the Gregorian calendar, with leap years every 4 years except century years not divisible by 400.
- Dates from 1583 to 9999 are supported. Earlier dates fall before the Gregorian calendar was widely used.
- Weekdays are Monday to Friday. Public holidays and local working weeks are not taken into account.
- Times of day are ignored. “Today” is your device’s current date.
Frequently asked questions
Should I include the end date?
It depends on what you are counting. The number of nights in a hotel stay, or days until an event, normally excludes the end date. A booking or leave period that runs “from Monday to Friday inclusive” includes both ends, which adds one day.
Does the weekday count include public holidays?
No. It counts every Monday to Friday. Public holidays differ by country, region and year, so subtract the ones that apply to you.
What happens when I add a month to January 31?
February has no 31st, so the date moves back to the last day of February: the 28th, or the 29th in a leap year. The calculator tells you when this happens.
Why are years and months added before weeks and days?
Months have different lengths, so the order matters. Adding months first, then days, matches how people usually read “1 month and 10 days from now”.
Do time zones or daylight saving time affect the result?
No. The calculator works with calendar dates only, not times, so a daylight saving change cannot add or remove a day.