Calculatrice de dates
The detailed guide below is currently available in English.
Counting days between two dates
The difference tab measures the span between a start date and an end date. By default the count works like a ruler laid between the two days: January 1 to January 2 is one day. Turning on "include end day" counts the final day as well, which is what you want when a hotel stay, rental, or event includes both the arrival and the departure date.
Business days and weekends
Business days count Mondays through Fridays only, skipping Saturdays and Sundays. The count follows the same include-end-day setting as the total, so a Monday-to-Friday span is 5 business days either way. Weekend days are simply the total minus the business days. Public holidays are not excluded, so adjust manually if your schedule depends on them.
Adding and subtracting time
The add-or-subtract tab walks forward or backward from a starting point by whole years, months, weeks, and days. Months are added calendar-style: one month after January 31 lands on February 28 in a common year, the same convention anniversaries and due dates use. All four boxes combine, so a shift of 1 year, 2 weeks, and 3 days can be applied in a single step.
Questions fréquentes
Does the day count include the start date?
The difference is measured like a ruler: from January 1 to January 31 is 30 days, counting January 31 but not January 1 itself. Check "include end day" if you need both endpoints counted, which makes that example 31 days.
How are business days counted?
Every Monday through Friday in the range counts as a business day, including the endpoints (when the end day is included). Saturdays and Sundays are never counted, and holidays are not removed automatically.
What happens when I add one month to the 31st?
The result clamps to the last day of the target month: adding one month to January 31 gives February 28, or February 29 in a leap year. The same rule applies to the 30th in February and to the 31st in 30-day months.