Date Difference Calculator: Days Between Dates
Calculate elapsed days, inclusive calendar days, and weeks between any two dates.
How to use Date Difference Calculator: Days Between Dates
Calculate the calendar difference between a start date and an end date for trips, contracts and project schedules.
Displayed values follow the definitions stated above.
Elapsed days and inclusive calendar days are different
Subtracting two dates gives elapsed days with the start at day zero. Tasks that count both endpoints, such as attendance or medication dates, usually add one.
Inclusive calendar days equal elapsed days plus one.
Recommended steps
- Enter the start and end dates.
- Decide whether the task needs elapsed or inclusive days.
- Use the business-days tool when weekends must be excluded.
How to interpret the result
- The same date has zero elapsed days but one inclusive day.
- The calculation uses calendar dates without times or time-zone offsets.
- Contracts and statutory periods can define whether the first day is included.
Frequently asked questions
How many days is January 1 to January 2?
One elapsed day, or two calendar days when both endpoints are counted.
Can the end precede the start?
The absolute difference is shown with a warning that the order is reversed.
Are public holidays excluded?
The date-difference tool counts every calendar date. The business-days tool can exclude weekends only or use its 2026 Korea and US holiday presets.