Date Calculator
Add or subtract years, months, weeks, and days from a date. See the resulting date, weekday, and calendar-day difference.
Your results
Choose a date and an amount of time to calculate the result.
How to use Date Calculator
- Choose a starting date, or use Today for your local calendar date.
- Select Add or Subtract and enter the whole years, months, weeks, and days.
- Calculate to see the resulting date and elapsed calendar days.
What is Date Calculator?
Calendar arithmetic follows the lengths of actual months and years. This calculator applies years first, then months, weeks, and days. If a year or month step would produce an invalid date, it uses the last valid day of that month. The calculation uses dates without time zones, so a daylight-saving change does not add or remove a calendar day.
- Add or subtract several calendar units together
- Handle leap years and month-end dates
- Read the weekday and total day difference
- Calculate locally without saving your dates
Dates, not elapsed clock time
This tool uses the Gregorian calendar across its supported date range. It does not apply a country's historical switch from another calendar, and a day count is not a measurement of elapsed hours across daylight-saving changes. Use the historical calculator when you need explicit Julian or BCE dates.
A practical example
January 31, 2024 + 1 month
February 29, 2024 · Thursday 29 calendar days later
Frequently asked questions
What happens when a month has fewer days?
The day is clamped to the last day of the target month. January 31 plus one month becomes February 28 in an ordinary year or February 29 in a leap year.
In what order are the units applied?
Years, then months, then weeks and days. A clamp at an earlier step is retained. For example, February 29, 2024 plus one year and one month becomes March 28, 2025.
Does this count business days?
No. All calendar days are included, including weekends and holidays. The Today shortcut reads your browser's local date.