Date Calculator
Count the exact number of days between two dates, or add and subtract days to find a deadline — with the weekday included.
Two calculators in one
Days between dates answers questions like "how many days until my deadline" or "how long was the project" and also expresses the result in weeks and days. Add or subtract days works the other way around: it takes a start date and a duration and gives you the exact calendar date — including the day of the week, which is often what actually matters.
Typical scenarios
- Visa rules: the date 90 days after arrival.
- Payments and contracts: a due date 30 or 60 days after the invoice.
- Events and trips: days remaining until a wedding, exam or departure.
- Health: days since a treatment started or between appointments.
All date math happens locally in your browser.
Frequently asked questions
How are days between two dates counted?
The calculator counts the number of full days from the start date to the end date. The start date itself is not counted: from January 1 to January 3 is 2 days.
Can I include the end date in the count?
If your task counts both endpoints — for example, hotel nights vs. days of stay — simply add 1 to the result.
Does it handle leap years and different month lengths?
Yes. The calculation uses real calendar dates, so February 29, 30-day and 31-day months are all handled automatically.
What is the "add or subtract days" mode for?
Enter a start date and a number of days to find a deadline or a past date — for example, "what date is 90 days from today" for a visa-free stay limit or a payment deadline.