Date Calculator
Count calendar days between two dates or add and subtract days from a date.
Your result
EVERYDAYEnter your values and select calculate.
On this page How it works & practical examples
How to use the Date Calculator
Difference mode subtracts the start date from the end date and excludes the start day. A negative result means the end date precedes the start date. Add/subtract mode uses a positive number to move forward and a negative number to move backward. Weekend days count exactly like weekdays; this is useful for elapsed calendar time rather than working-day deadlines.
The calculation
Worked example
January 1 to February 1, 2026 is 31 days. Adding 30 days to January 1 produces January 31.
Assumptions and limits
Dates are converted to UTC date boundaries for arithmetic, avoiding daylight-saving hours that could otherwise affect a day count. No local holiday calendars or business-day exclusions are applied. Months are not treated as fixed lengths. The input and resulting dates must remain between 1900 and 9999, with added days limited to 365,000 in magnitude.
Common questions
Are both endpoint dates included?
No. Difference mode uses end minus start. For an inclusive count of a forward interval, add one day to the displayed difference.
Can I subtract days?
Yes. Choose add/subtract mode and enter a negative number of days.