Date Calculator
Count the days between two dates, or add and subtract days, weeks, months and years and see the resulting weekday.
How to use
- Choose a mode at the top — ‘Date difference’ or ‘Add or subtract’.
- Date difference: pick a start and an end date to see total days, weeks, months and years.
- Switch on ‘Include the start day’ to count the first date as day one.
- Add or subtract: set a base date, an amount and a unit to get the resulting date and weekday.
FAQ
Is the start date counted in the difference?
Not by default. Switch on ‘Include the start day’ to count it as day one.
What happens if I add one month to 31 January?
A date that does not exist in the target month is clamped to that month's last day, so 31 January + 1 month is 28 February (29 in a leap year).
How are months and years counted?
On the real calendar. Months means whole months, ignoring leftover days.
Are weekends and holidays counted?
Yes — only calendar dates are counted, so weekends and holidays are included.
How do I count down to a date (D-day)?
In ‘Date difference’, set the start date to today and the end date to your target day. With ‘Include the start day’ off, the total is the number of days left — tomorrow is 1 day away.
Can it count only weekdays?
Yes. ‘Weekdays (Mon–Fri)’ leaves out Saturdays and Sundays. Public holidays are not removed, so subtract them yourself if any fall in the range.
Are leap years handled?
Yes. It counts on the real calendar, so 29 February is included in leap years: 1 February to 1 March 2028 is 29 days.
Can I see the result as years, months and days?
Yes. ‘Years · months · days’ splits the span into whole years, whole months and the days left over — handy for length of service or a baby's age in months.