Two questions cover almost every date problem: how far apart are these two dates, and what date is N days from here. This calculator answers both, in calendar days and business days, and tells you the weekday of the result so you are not planning a delivery for a Sunday.
How it is calculated
- Days between dates is the plain difference: from the 1st to the 31st of the same month is 30 days. Turn on "count the end date too" to get 31, the way you would count days of a holiday or days of a course.
- The calendar difference (years, months, days) counts whole months first, so the 31st to the 28th of February is 28 days, not one month.
- Business days count Monday to Friday and ignore public holidays, which differ by country. Subtract any holidays in your range yourself.
- Adding months keeps the day of the month where possible: January 31 plus one month is February 28 (or 29), the last day of the shorter month, not March 3.
- Adding business days skips weekends: Friday plus one business day is Monday.
Examples
From March 1, 2026 to June 1, 2026: 92 days, exactly 3 months, 13 weeks and 1 day, 65 business days. Ninety days after March 1, 2026 is May 30, a Saturday; 90 business days after it is July 3.
Common uses
Payment terms ("net 30"), notice periods, project deadlines, pregnancy weeks, visa and passport validity (many countries require six months left), returns windows, contract renewals, and how many days until an event. For counting back from a due date use the subtract mode.
Frequently asked questions
How do I count days between two dates?
Subtract the earlier date from the later one. The calculator handles month lengths and leap years for you and shows the answer in days, weeks and business days.
Should I count the start day, the end day, or both?
It depends on the question. Nights in a hotel: neither end (check-in to check-out). Days of a trip or a course: both. Deadlines like "within 30 days" usually start counting the day after. Use the "count the end date too" switch for the inclusive version.
How are business days counted?
Monday through Friday. Public holidays are not excluded because they vary by country and region; subtract them from the result if they fall in your range.
What date is 90 days from today?
Choose "Add or subtract", enter 90 days, and the result shows the date and its weekday. Today’s date is filled in by default.
What happens when I add a month to the 31st?
You get the last day of the next month, because it has no 31st. This is the convention used by banks and most software.
Sources
By Calcelate Team. Formula from the sources above.
- 2026-09-14 · Formula and texts checked