How to use this calculator
- Enter the start and end dates.
- Choose whether the first and last day count.
- For 'how many days until', keep the start included and the end excluded (the default).
Formula
With both dates excluded you count only the days strictly between them; including each endpoint adds one day.
Days (start included, end excluded) = end − start
Both included = end − start + 1
Both excluded = end − start − 1
Example
- 1 to 10 December: 9 days with the end excluded, 10 days with both included.
- A hotel stay from the 1st to the 10th is 9 nights.
Frequently asked questions
Which option should I choose?
For durations and 'days until', count the start but not the end. For counting calendar days you're present (such as a trip or a contract period), include both.
Does it handle leap years?
Yes, every calendar day including February 29 is counted.
Can I count only working days?
The weekday count is shown below the result. For holidays, use the business days calculator.