Date Calculator
Add or subtract days, weeks, months, and years from any date, or find the exact difference between two dates.
Table of Contents
How to Use the Date Calculator
- Choose a mode: find the difference between two dates, or add/subtract years, months, weeks, and days from a single date.
- Enter your dates and the amount of time to add or subtract. The result updates instantly.
- Use the calendar picker or type a date directly. Results include the resulting date, the day of the week, and the total number of days.
What Is a Date Calculator?
A date calculator works with calendar dates the way a normal calculator works with numbers. It can add or subtract a span of time from a date, or measure the exact gap between two dates.
This is useful for deadlines, project timelines, contract periods, countdowns, and anywhere you need to shift a date by a known amount of time or measure how long something lasted.
How Date Math Works
When adding or subtracting months and years, the calculator keeps the same calendar day when possible. For example, adding one month to January 31 lands on February 28 (or 29 in a leap year).
The difference between two dates is counted the standard calendar way — in years, months, and days — and also as a single total of whole days.
Weeks and days are derived from the exact elapsed time, so the results stay consistent with real calendar arithmetic.