What does a day-of-week calculator do?
It maps a Gregorian calendar date to its weekday and provides supporting calendar details such as day-of-year, quarter and leap-year status.
How does leap-year status affect the result?
Leap years contain February 29, which shifts the weekday alignment of later dates in that year.
What does day of year mean?
Day of year counts January 1 as day 1 and continues through 365 or 366 in a leap year.
Can historical calendar dates differ from this result?
This calculator applies the Gregorian calendar consistently. Very old local historical dates may have been recorded under other calendar systems before local adoption of the Gregorian calendar.
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Frequently asked questions
Yes. Select any supported future date.
Yes. The tool supports Gregorian dates in its input range.
Yes. Saturday and Sunday are classified as weekend days.
Yes.
Yes. The result identifies Q1 through Q4.
Yes. Gregorian leap-year rules are applied.
No. A date-only weekday does not require a time zone.
Yes. The calculation uses Gregorian calendar rules.
Sources and methodology
This calculator uses transparent browser-side date/time arithmetic. The references below provide standards or official context relevant to the calculation.
ISO — ISO 8601 date and time formatInternational standard context for unambiguous Gregorian dates, times, UTC and intervals.ISO — ISO 8601-1:2019Current published ISO standard for Gregorian date and time representations.
Date and time scope: Calendar, time-zone, holiday and scheduling conventions can differ by jurisdiction or organization. Check authoritative rules when a deadline, legal right, payroll event or travel schedule depends on the exact result.
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