Date Calculator

Result date

Calculate calendar dates without converting them to approximate month or year lengths. Add or subtract a duration, find the exact difference between dates, or count working days.

Compare dates or add and subtract calendar or working days. Choose which days count as weekends and enter any holidays.

Calendar-aware date arithmetic

Years and months are applied before weeks and days. When the destination month is shorter, the day is clamped to the final valid day of that month. For example, adding one month to January 31 produces the last day of February.

Date difference and business days

Date difference shows elapsed days and calendar duration. Working-day modes use your selected weekends and holidays.

How to calculate dates

  1. To add or subtract days, choose Add or subtract, enter the start date, set years, months, and weeks to zero, and enter the days.
  2. Choose Date difference and enter two dates. Enable including both dates when needed.
  3. Choose Business days to count a range, or Add/subtract business days to find a date. Set weekends, holidays, and whether to count the start date.

Date Calculator FAQ

How do I find the date 30 days from a starting date?

Choose Add or subtract and Add. Enter the starting date, set years, months, and weeks to zero, and enter 30 days. The result includes the date and weekday; the starting date is day zero.

Are the start and end dates included?

The default is elapsed calendar days, including weekends. Enable counting both dates to add one day; the same date then counts as one. Use Business Days to exclude weekends.

What happens when a month does not have the same day?

The result uses the last valid day of the target month. January 31 plus one month is February 28, or February 29 in a leap year. Years and months are applied before weeks and days.

Are public holidays excluded automatically?

No. Saturday and Sunday are excluded by default; you can change the weekend days. Add holidays as YYYY-MM-DD, separated by spaces, commas, or line breaks. A holiday on a weekend is excluded only once.

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