Date CalculatorCalculate Date Difference
Calculate exactly how many days, weeks or months lie between two dates.
With our date difference calculator, you can easily determine time spans. Whether you are planning project deadlines or creating countdowns for events, you always get precise results taking leap years into account.
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Date difference: calculating days between two dates
The date difference tells you how much time lies between a start and an end date. The calculator returns the span in days, weeks and months and automatically accounts for varying month lengths and leap years.
A key question is whether the first day is counted. Counting both endpoints (inclusive) gives one more day than counting only the full days in between (exclusive). For stays – a hotel booking or a trip – the number of nights, i.e. the exclusive difference, is usually what matters.
Beyond the raw day count, the ISO 8601 calendar week is often useful: it starts on Monday, and the first week of a year is the one containing the first Thursday. This makes spans that cross year boundaries unambiguous.
Frequently asked questions
Is the first day included?
By default the calculator counts the full days between the two dates (exclusive). If you want to include both endpoints, add one day.
How many weeks and months is that?
The calculator also converts the day difference into weeks (÷ 7) and months. Because months vary in length, the month figure is a calendar average.
Does the time zone matter?
No. The calculation is based on pure calendar days, so the duration between two dates is the same regardless of your time zone.
Are leap years taken into account?
Yes. If February 29 falls within the span it is counted automatically, because the calculator maps the full Gregorian calendar.