Date Calculator
Find days between dates or add and subtract years, months, weeks, and days
Understanding Date Calculations
Use this page for calendar spans, deadline math, and date planning
What this calculator helps with
- Find the number of days between two dates for deadlines, events, travel plans, or project timelines.
- Add years, months, weeks, and days to a start date when planning renewals, due dates, or milestones.
- Subtract calendar time from a date when working backward from a launch, appointment, or cutoff.
How it works
Date differences compare local calendar dates, not clock times, so daylight saving time changes do not affect the day count. Add and subtract mode applies years and months first with end-of-month clamping, then applies weeks and days.
Quick Examples
Common ways to use date arithmetic in everyday planning
Date Calculator FAQ
Common questions about date ranges, inclusive counting, month math, and leap years.
Should I include the end date?
Use inclusive counting when both the start and end dates should count, such as a stay from Monday through Friday. Leave it off for elapsed time between two dates.
Does the calculator count calendar days or business days?
This calculator counts calendar days. Weekends and holidays are included in the total unless you adjust the dates manually.
How are months handled when adding dates?
Month math follows the calendar. If the target month has fewer days, the result is clamped to the valid day in that month.
Are leap years included?
Yes. The date calculation uses real calendar dates, so leap days and different month lengths are included automatically.
Can I add weeks and days to a date?
Yes. Switch to add or subtract mode, then enter years, months, weeks, and days to move the date forward or backward.