How to count the days between two dates
Enter a start date and an end date and press Calculate. The result is the number of days you would have to move forward on the calendar to get from the first date to the second. For example, from March 1 to March 31 is 30 days. If you want to count both the first and the last day — “March 1 to March 31 inclusive” — tick Include the end date and the answer becomes 31.
Inclusive or exclusive: which do I need?
| Situation | Include end date? |
|---|---|
| How many days until an event | No |
| Age in days, time since an event | No |
| Number of days of a holiday or event “from … to …” | Yes |
| Days of leave covering both first and last day | Yes |
| Nights in a hotel stay | No (nights = days between check-in and check-out) |
Counting days by hand
To count manually, count the remaining days in the start month, add the full months in between, then add the day number of the end date. From March 15 to June 10: 16 days left in March + 30 (April) + 31 (May) + 10 = 87 days. It is easy to slip on 30- and 31-day months and on leap years, which is why the calculator converts each date to a day number and subtracts.
Weekdays between dates
The result also splits the days into weekdays (Monday to Friday) and weekend days. That is useful for estimating working days, though public holidays are not removed from this count — use Add Days to Date with business days and US holidays if you need that.
For durations in hours, minutes and seconds use the Date to Date Calculator; to count down from today use Days Until Date. The main Date Calculator also adds and subtracts dates.