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Free Date & Time Tools

Look up a date's ordinal day or ISO week, or count weekdays across a date range.

12 free toolsNo sign-upBrowser-based

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ISO weeks can belong to a different week-year near New Year. The business days tool counts weekdays inclusively but does not exclude regional holidays.

Date & Time

12 tools

Day of Year CalculatorFind a date's ordinal day and days left in the year.Week Number CalculatorFind the ISO week number and week-year of a date.Business Days CalculatorCount Monday–Friday dates in an inclusive range.Unix Timestamp ConverterConvert Unix seconds or milliseconds to a UTC date and back.Timezone ConverterConvert a local date and time between IANA time zones.Time Zone Meeting PlannerSee one meeting's start and end across multiple time zones.ICS to CSV ConverterExport iCalendar events as CSV rows. Review recorded dates, time-zone identifiers, descriptions and recurrence rules without expanding repeating events.CSV to ICS ConverterBuild an iCalendar file from a CSV event list. Use UTC timestamps or all-day dates, review each event and import the downloaded file into your calendar.Age CalculatorFind complete calendar years and months using end-of-month clamping, then count remaining UTC calendar days.Date Difference CalculatorSubtract UTC date-only timestamps and divide by 86,400,000 milliseconds.Date CalculatorApply the year and month offset together, clamp to the destination month, then add UTC calendar days.Time Duration CalculatorSubtract two 24-hour clock times; optionally move an earlier end time into the next day.

How to choose

Day of Year gives the ordinal position of a calendar date, including February 29 in leap years. Week Number follows ISO 8601: weeks start on Monday and week 1 contains January 4. Dates near January 1 can therefore have an ISO week-year different from their calendar year.

Business Days counts Monday through Friday across an inclusive start and end date. It is useful for a quick weekday count, but public holidays, company closures, and regional working-week rules are not included. Check those separately for payroll or contractual deadlines.

Common questions

Are the start and end dates both counted?

Yes. Business Days includes both endpoints when they fall on a weekday.

Why is January 1 sometimes in last year's ISO week?

ISO weeks use a week-year based on the first week containing January 4, which can differ from the calendar year near New Year.

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