How to count days between dates
Understand inclusive date counting, leap years and the difference between calendar days and 24-hour periods.
Subtract the start date from the end date to count calendar days. Enable “Include the end date” to count both dates; the result then increases by one.
Calendar days are not always 24 hours
This tool compares dates, not timestamps. A local day can be 23 or 25 hours when clocks change. For flight durations or timed deadlines, use exact timestamps with their time zones.
Choose the counting convention first
October 1 to October 2 is a difference of one day. Counting both dates covers two calendar dates. Booking nights, attendance days and contractual deadlines may use different conventions; check the rule before relying on a number.
Leap days are included automatically
In the Gregorian calendar, years divisible by 4 are leap years, except years divisible by 100 unless they are also divisible by 400. Thus 2000 is a leap year, but 2100 is not. The difference between February 28 and March 1, 2024 is two days.
Weekends and holidays are not removed
The result includes every calendar day. Business-day calculations need a jurisdiction, weekend rules and a verified holiday calendar. Subtracting Saturdays and Sundays is not sufficient for every country.
Method references
Updated: October 3, 2026. Status: pre-release; not independently audited.