How to use this calculator
Enter your start and end dates. Swap them to check the reverse interval, or count both dates with the inclusive option.
The default excludes the starting date and includes the destination date. Counting both dates adds one to the absolute span. Reversing the dates gives a negative result.
Worked example
October 9 to October 12, 2026 is 3 days. Counting both dates gives 4 days; the reverse interval is −3 days by default.
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