How to use this date difference calculator
Use the date difference calculator for deadlines, study plans, project timelines, events, and general date planning.
The default result counts the elapsed time between dates. You can also include both the start and end date when that matches your use case.
Formula
Date difference = End date − Start date
Worked example
From 1 September to 11 September there are 10 elapsed days, or 11 days when both dates are counted inclusively.
Step-by-step
- Choose the start date.
- Choose the end date.
- Select whether to count both dates, then calculate.
Frequently asked questions
What does inclusive counting mean?
Inclusive counting adds one day so both the start and end dates are included.
Are leap years included?
Yes. The browser Date API works with actual calendar dates.
Can the end date be before the start date?
The tool will ask you to correct the dates instead of returning a negative duration.