How to use this calculator
Compare dates with calendar years, months, weeks and days, or add/subtract a calendar interval. Year/month offsets clamp to the target month’s last day, then week/day offsets apply. Working-day offsets skip your selected weekend and explicit holiday dates.
- Enter date task, start date, end date and review the remaining options.
- Select Calculate or change a value to update the result. Read the result label and units before copying.
- Use Reset to restore the worked starting values.
Formula and method
Gregorian dates, years 0001–9999. Date-only UTC arithmetic. Optional US holiday pattern supports 2021–2099, projects current rules, and excludes DC-only Inauguration Day. Future law changes and employer-specific observances are not predicted. Working-day offsets are limited to 36,600 days.
Worked example
January 1 to February 1, 2024 is 31 days excluding the end date.
Questions about date difference calculator
Does inclusive counting change the result?
Yes. January 1 to January 2 has one elapsed calendar day. Including both dates counts two dates. The tool gives days and full weeks; it does not treat every month as a fixed number of days.
What assumptions should I check?
Gregorian dates, years 0001–9999. Date-only UTC arithmetic. Optional US holiday pattern supports 2021–2099, projects current rules, and excludes DC-only Inauguration Day. Future law changes and employer-specific observances are not predicted. Working-day offsets are limited to 36,600 days.
Are my inputs saved?
Calculations run in your browser. We store only tool IDs for favorites and recent tools. A calculation link contains your inputs only when you explicitly choose to copy one.