Deadlines, countdowns, rental periods and project plans all start with one question: how many days from here to there?
How it is counted
The Date Difference Calculator subtracts the two dates. From 1 January 2026 to 25 December 2026 is 358 days, which is about 51.1 weeks. It counts the days that pass between the two dates, so the start day is not counted. If you need both the first and last day included, add 1.
Using the calculator
- Enter the start date and the end date.
- Read the number of days and the approximate number of weeks.
Leap years are handled automatically, since the tool uses the calendar.
Business days
The result is calendar days, including weekends and holidays. To estimate working days, divide the weeks by one and multiply by five, then remove local public holidays. That is an approximation, so count the holidays that apply to you.
Practical examples
- A 30-day notice period starting on 10 March ends on 9 April. Use add days to a date for that.
- A project from 1 February to 31 March spans 58 days in a non-leap year, or 59 in a leap year.
- Counting down to an event: enter today and the event date.
Frequently asked questions
Can the end date be earlier than the start?
Reverse the two and read the number as a gap; the order tells you the direction, not the size.
Why is “weeks” marked approximate?
Because it is days divided by 7 and shown as a decimal, not a count of whole calendar weeks.