Date Calculator
Find days between dates or add and subtract years, months, weeks, and days
Calendar rule: Month and year arithmetic keeps calendar dates intuitive. If a target month has fewer days, the result clamps to the last valid day of that month.
Date Difference
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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
May 1 to May 31
30 days, or 31 days when including the end date
Add 1 month to January 31, 2026
February 28, 2026
Subtract 2 weeks from June 15, 2026
June 1, 2026