This calculator answers the two date questions that come up constantly and that nobody can do reliably in their head: how long is it between these two dates, and what date falls a certain distance from this one. It counts calendar months properly — a month after 31 January is not simply thirty days later — handles leap years, and gives you the count in business days as well as plain days, which is what notice periods, delivery estimates and deadlines are usually written in.
Every day except Saturday and Sunday, counting the start date and stopping before the end date. Public holidays are not deducted, because they differ by country and by year — subtract those yourself for the region you are in.
Because months are not the same length. The breakdown walks the calendar: it counts whole months from the start date, then the days left over. That is why 31 January to 1 March reads as one month and one day rather than a fixed number of days.
The date rolls into the next month rather than clamping. One month after 31 January lands on 2 or 3 March, depending on the year, because February has no 31st. If you need it to clamp to the last day of the month, subtract the difference by hand.
Yes. The calculation uses the browser's own calendar, so 29 February exists in the years it should and day counts across it come out right.
The day, week and business-day counts ignore the time and compare whole calendar days, so a time zone change cannot shift the answer by one. The hours and minutes figures do use the exact moments.