Date Difference Calculator
Find the number of days, weeks, months and years between any two dates.
The Date Difference Calculator is being built
This free calculator will appear here shortly. Meanwhile, the formula and ranges below show exactly how it works.
- Start date
- End date
- Include end date (yes / no)
- Days
- Weeks + days
- Months + days
- Working days
About the Date Difference Calculator
Handy for counting medicine courses, days since symptoms began, follow-up dates and test intervals.
Formula explained
Days between = end date − start date
Tick “include end date” to count both days (adds 1). Weeks = days ÷ 7. Working days leave out Saturdays and Sundays.
Frequently asked questions
Should I include the end date?
Include it when counting a course — for example, a 5-day course from Monday to Friday. Leave it out when counting time passed.
Does it work across years?
Yes. It counts the exact number of days, including leap years.
Medical disclaimer: These tools give general information and estimates only. They are not a diagnosis and do not replace advice from a qualified doctor. Always talk to your doctor about your results, and seek urgent medical help in an emergency.