Date Calculator
Count days, add months, work out an exact age or a deadline in business days.
Result
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On the calendar
How this is calculated
Dates are treated as whole calendar days in the Gregorian calendar, with no time of day, so daylight-saving changes and time zones never shift a result.
- Days between is the end date minus the start date. Tick "count the end date" to include both days, for example when counting the days of a trip.
- Months and years: a month is complete when the same day of the month comes round. When that day does not exist (the 31st in a 30-day month, or 29 February in a common year), the last day of the month counts. Someone born on 29 February turns a year older on 28 February in common years by this rule; some laws use 1 March instead.
- Business days are Monday to Friday. US federal holidays follow 5 U.S.C. 6103 with the federal employee rule: a holiday that falls on a Saturday is observed the Friday before, and on a Sunday the Monday after. Private employers and other countries have different holidays.
- Week numbers follow ISO 8601: weeks start on Monday, and week 1 is the week with the year's first Thursday.