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Date Calculator
Add or subtract days, weeks, months, and years from any date. Or calculate the exact difference between two dates.
Date Calculator
Select a start date to calculate
How to Use
- Choose a mode — "Add / Subtract" to calculate a future or past date, or "Date Difference" to find the gap between two dates.
- Select dates — Pick a start date using the date picker. For difference mode, also pick an end date.
- Enter values — In add/subtract mode, enter the number of years, months, weeks, and/or days to add or subtract.
- View results — See the calculated date with detailed information including day of week, week number, and ISO format.
Frequently Asked Questions
How does the calculator handle leap years?
The calculator correctly accounts for leap years (February 29). When adding months to a date like January 31, if the target month has fewer days (e.g., February), it adjusts to the last day of that month (February 28 or 29).
Does weeks × 7 equal exactly 7 days?
Yes. Weeks are converted to days (1 week = 7 days) and added to the day count. This is separate from months and years, which are calculated based on calendar months.
What is the maximum range?
You can add or subtract up to 1,000 years, 120 months, 5,200 weeks, and 36,500 days. The calculator works with dates from year 1 to year 9999.
Does the date difference include the end date?
Yes. The difference calculation includes the end date. For example, the difference between January 1 and January 2 is 1 day. If you need to exclude the end date, subtract 1 from the total.
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