Date Calculator
Count days between dates, or add and subtract days from a date.
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How are days counted?
The default result is the end date minus the start date. For example, February 28 to March 1 in a leap year is 2 days apart, or 3 days including both endpoints. If the end date is earlier, the result is negative. Inclusive counting increases the absolute day count by one.
Will timezones or daylight saving change the answer?
No. This tool works with Gregorian calendar dates, not hours or timestamps. It supports years 0001 to 9999. It does not count business days or public holidays and does not approximate months as 30 days.
Count calendar days for a plan
Choose the two dates and decide whether both endpoints should count. For a deadline offset, switch to adding or subtracting days from a starting date.
Example and expected result
September 16 to September 20 is 4 days apart, or 5 days when both dates count. These are calendar days, including weekends. Business-day rules and public holidays need a different calculation.