Date Calculator
Add or subtract days, weeks, months, or years from any date. Or calculate the duration between two dates in days, weeks, months, and years.
How the date calculator Works
This tool uses the following formulas to compute results:
Add days: Result date = Start date + N daysDuration between dates: End date − Start date (in days)Weeks = Total days ÷ 7; Months ≈ Total days ÷ 30.44
About Date Calculator
Add or subtract days, weeks, months, or years from any date. Or calculate the duration between two dates in days, weeks, months, and years.
Use the inputs above to calculate your result instantly. Results update automatically as you type. All calculations happen in your browser, so your data is never sent to a server.
Frequently Asked Questions
Does this calculator handle leap years?
Yes. The calculator uses actual calendar arithmetic, so February 29 is correctly included in leap years.
How are months added when dates don't match?
Adding one month to January 31 gives February 28 (or 29 in leap years), since February has fewer days.
What is the difference between calendar days and business days?
Calendar days include weekends and holidays. Business days exclude weekends and typically holidays, depending on regional conventions.
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