Date Calculator
Calculate durations, business days, ages, and dates before or after another date.
Difference between dates
0 calendar days
0 weekdays · 0.0 weeks
Add or subtract days
9/19/2026
How to calculate dates and differences
- Compare two dates. Choose a start and end date to see calendar days, weekdays and weeks.
- Or do date arithmetic. Choose a start date and enter a number of days.
- Go backward if needed. Use a negative number to calculate an earlier date.
What happens to your data
All date math runs locally in your browser — nothing is sent to a server.
What this calculator supports
DifferencesCalendar-day differences between two dates
WeekdaysWeekday counts between dates
WeeksConversion to whole weeks
ArithmeticAdd or subtract any number of days from a date
ProcessingEntirely in your browser tab
Common reasons to use this calculator
- Figure out how many days are left until a deadline or event.
- Calculate a due date a fixed number of days from today.
- Check how many weekdays fall between two dates.
- Work out what date it will be, or was, a given number of days away.
Frequently asked questions
Is my data uploaded anywhere?
No — all calculations run locally in your browser.
Does it account for public holidays?
No — weekday totals exclude Saturdays and Sundays but do not account for public holidays.
Can I calculate a date in the past?
Yes — enter a negative number of days to calculate an earlier date.
Does it also show weeks, not just days?
Yes — the calendar-day difference is also converted into whole weeks.
Last reviewed: August 2026