Two calculators in one
Days between dates: pick a start date and an end date. You'll get the total number of days, the same span in years, months and days, the number of full weeks and the number of weekdays (Monday to Friday). By convention the end date is not counted; if you need both the first and last days included, as for a hotel stay or event, use the "Including end date" figure.
Add or subtract: leave the end date blank, choose Add or Subtract, enter an amount and pick days, weeks, months or years. The result is the new date and its day of the week. You can also fill in both parts to see a span and a shifted date together.
How dates are counted
The calculator works with real calendar dates, so month lengths and leap years are handled automatically. Calculations use whole calendar days, which avoids the one-hour glitch that daylight-saving changes can cause in some spreadsheet formulas. When you add months, the day of the month is kept where possible; adding one month to 31 January rolls over into early March because February has no 31st.
Business days
The weekday count excludes Saturdays and Sundays but does not know about public holidays, which differ by country and region. Subtract any holidays that fall within your range to get an exact working-day total.
Common uses
- Counting down to a vacation, wedding, exam or product launch.
- Working out a deadline such as "30 days from the invoice date" or "90 days after purchase".
- Calculating notice periods, warranty expiry dates or contract terms.
- Finding how many days a loan, deposit or project has been running.
- Planning a schedule by adding weeks to a start date.
To measure a person's age precisely, the age calculator is more convenient.
Frequently asked questions
How many days are between two dates?
Enter both dates and the calculator returns the total. The end date itself is not counted unless you use the "Including end date" figure.
Does the calculator count weekends?
The main total includes all days. A separate weekdays figure excludes Saturdays and Sundays.
Are public holidays excluded?
No, holidays vary by location. Subtract them manually from the weekday count.
What happens when I add a month to January 31?
JavaScript dates roll over, so the result moves into early March. Check month-end deadlines carefully.
Last reviewed 2026-10-27. This date calculator is provided for general information; verify important decisions with a qualified professional.