Date Calculator
Count days, jump forward or backward in time, or get an exact age.
How it works
All calculations use pure calendar dates (no times of day), so daylight saving and time zones can never skew a result. Leap years are handled by your browser’s own calendar engine. “Days between” counts the gap from start to end; tick include the end date when you need both endpoints counted, for example for event runs or rental periods.
FAQ
Should I include the end date?
For deadlines and countdowns, usually no. March 1 to March 10 is 9 days of elapsed time. For bookings, rentals or “how long did the event run”, include it: that’s 10 days. Pick whichever matches your use case.
How does adding one month work?
Calendar-aware: January 31 + 1 month lands on February 28 (or 29 in leap years) rather than spilling into March, which is what most legal and billing contexts expect.
Does the age calculator handle leap-day birthdays?
Yes. Someone born on February 29 has their age advance on March 1 in non-leap years, which is the common legal convention.