About the Date Difference Calculator
Count the exact days between two dates — plus the same gap expressed in weeks, months, and approximate weekdays. Handy for deadlines, leases, pregnancies, and project plans.
The dates you enter stay in your browser. Nothing is sent to a server, which also means the tool works offline-ish once the page has loaded, and there is no log of what you looked up.
How to use it
- Pick a start date.
- Pick an end date.
- Read the gap in days, weeks and months.
Why two tools can give different month counts
Days are unambiguous — a day is a day. Months are not: they run from 28 to 31 days, so any 'months between' figure is an approximation unless the calculator says which convention it uses.
This tool reports the exact day count first, because that is the number you can rely on for deadlines, notice periods and contracts.
A worked example
From 15 January 2026 to 1 September 2026:
- 229 days
- That is 32 weeks and 5 days
- Roughly 7.5 months
Note that 2026 is not a leap year. Cross 29 February in a leap year and the day count gains one, which is exactly the sort of thing that goes wrong when people count on their fingers.
Common mistakes
- Forgetting whether the end date should be counted. A 30-day notice period starting on the 1st usually ends on the 30th, not the 31st.
- Assuming a month is 30 days when calculating interest or rent. Most agreements use actual days.
- Ignoring leap years on multi-year spans — they add a day each.
Questions people ask
Does it count both the start and end date?
The result is the number of days between the two dates. If your situation counts the first day as day one, add one.
Can I work out a date in the future?
Use the Age Calculator for a running count from a fixed date, or set the end date forward here to see the gap.
Are leap years handled?
Yes. The day count is exact and includes 29 February wherever it falls in the range.