📅 Date Difference

Counting days between two dates

This calculator returns the number of days from the first date to the second. It measures the interval, so 1 March to 8 March is seven days — the span between them, not the eight dates involved.

That distinction matters more than it sounds. "Within 10 days" in a contract and "10 days inclusive" mean different things, and legal deadlines usually specify which convention applies. When a rule says a period runs from a given date, many legal systems exclude that first day and begin counting from the following one.

Calendar days versus business days

Business day counts exclude weekends and, usually, public holidays. Because holidays vary by country and even by region, a universal business-day count is not possible without knowing where you are.

The practical consequence is that "five business days" can mean anything from seven to eleven calendar days depending on where the weekend and holidays fall. Around Christmas, Easter, Golden Week, or Lunar New Year, the gap widens considerably. If you are promising a turnaround, quoting calendar dates avoids the ambiguity entirely.

Why month arithmetic is unreliable

Months range from 28 to 31 days, so converting a day count into months always involves an approximation. Dividing by 30 is the usual shortcut, but it overstates the number of months across a full year by about five days' worth.

For anything contractual — notice periods, subscription terms, interest accrual — work in actual dates rather than converted months. A "three month" notice given on 30 November has an ambiguous end date, since 30 February does not exist. Most conventions resolve this to the last day of the target month, but not all of them do.

Weeks are the one clean unit: exactly seven days, always. If you need a rough sense of scale, 100 days is about 14.3 weeks and 1,000 days is a little over two years and nine months.

Common questions

Should I include both the start and end date?

It depends entirely on what you are measuring. For a hotel stay you count nights, not dates. For a holiday allowance you usually count days worked, which includes both ends. Decide which you need before trusting any tool.

How do I count only weekdays?

Divide the total by seven to get whole weeks, multiply by five, then add the weekday remainder. The result still ignores public holidays.

Can I go backwards in time?

Yes — put the later date first and the result is simply negative, representing days elapsed rather than days remaining.