Date Calculator
This date calculator adds or subtracts days, weeks, and months from a start date, or counts whole days between two dates. Business-days mode skips Saturday and Sunday.
How to use
- Choose add or subtract, then enter a start date and a whole number of days, weeks, or months.
- Or switch to days between dates and enter a start and an end date.
- Turn on business days to skip Saturday and Sunday. Holidays stay in the count, and months still follow the calendar.
Formula
Whole calendar days are the date difference, not a count that includes both endpoints. Adding days or weeks uses the calendar. Business-days mode skips Saturday and Sunday and does not skip holidays. One business week is 5 weekdays. Months are calendar months, and the day clamps when the target month is shorter.
Example. Adding 10 days to January 15, 2026 lands on January 25, 2026. January 16, 2026 is a Friday; adding 1 business day lands on Monday, January 19, 2026. February 28, 2024 plus 1 day is February 29.
Frequently asked questions
How do I find days between two dates?
Enter a start and end date. The tool counts whole calendar days between them. January 1 to January 11 is 10 days.
Can I add business days only?
Yes. Business-days mode skips Saturday and Sunday. It does not skip public holidays. One business week is 5 weekdays.
Does it handle leap years?
Yes. February 29 is included when the year is a leap year. Adding one month to January 31 lands on February 29 in a leap year and February 28 otherwise.
What timezone is used?
Dates are treated as calendar dates without time-of-day, so timezone offsets do not change the day count.
Can I subtract days from a date?
Yes. Choose subtract and enter the number of days, weeks, or months.
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