Date Calculator
Add or subtract days, or find the exact duration between two dates.
Duration
2 months, 29 days
- Total days
- 90
- Total weeks
- 12 wk 6 d
- Business days (Mon–Fri)
- 64
About the Date Calculator
A date calculator answers two everyday questions: how long is it between two dates, and what date falls a certain time before or after another. Use the Difference mode to count the gap between a start and end date — useful for project timelines, notice periods, pregnancy weeks, or how many days until an event. Use the Add / Subtract mode to shift a date forward or back by years, months, weeks and days — handy for deadlines, renewal dates and reminders.
The difference is shown both as a calendar duration (years, months and days, the way people naturally describe a span) and as exact totals: total days, total weeks, and the number of business days (Monday to Friday), which matters for working-day deadlines and SLAs. Because months vary in length and leap years add a day, the calculator works in whole calendar months and clamps sensibly — adding one month to 31 January lands on the last day of February, not an invalid date.
Everything updates instantly, and you can share a link that reproduces the exact dates and interval you entered.
Frequently asked questions
How do I find the number of days between two dates?
Choose the Difference mode and enter a start and end date. The calculator shows the gap as years, months and days, and also as the total number of days and weeks between them. The order doesn't matter — it tells you if the end date is before the start.
What counts as a business day?
Business days are Monday to Friday. The calculator counts the weekdays that elapse between your two dates, excluding Saturdays and Sundays. It does not account for public holidays, which vary by country.
How does adding months handle different month lengths?
It adds whole calendar months and clamps the day to the end of the target month when needed. For example, 31 January plus one month gives 28 February (or 29 in a leap year), since there is no 31 February.
Can I subtract time as well as add it?
Yes. In Add / Subtract mode, switch the direction to Subtract and enter any combination of years, months, weeks and days to move the date backwards. The result shows the new date and the day of the week it falls on.