Day of the Week Calculator

Find what day of the week a date falls on.

Date

Results update as you type.

Day of the week

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Weekend?—

How it works

A day of the week calculator names the weekday for any date, past or future, and tells you whether that date is a weekend. Give it a date and it returns Monday through Sunday, so you can answer "what day was I born," "what day does the deadline land on," or "is that anniversary on a weekend" without paging through a calendar. It works entirely from the date's position in the repeating seven-day cycle of the Gregorian calendar. Knowing the weekday changes how a date is treated. A payment or filing due on a Saturday usually rolls to the next working day, an event on a Friday reads very differently from the same event on a Tuesday, and shift and delivery planning depends on which days are weekdays. Working the weekday out by hand means counting from a known reference and adjusting for leap years, which is fiddly and error-prone over long spans. The calculation is exact because it maps the date to a continuous day count and reads off its remainder within the seven-day week, so leap days are already accounted for. The weekend flag uses the standard Saturday–Sunday convention. Genealogists confirming a birth day, event planners choosing dates, and anyone checking whether a deadline falls on a working day rely on a day of the week calculator for an instant, dependable answer.

Formula

weekday = position of the date in the seven-day Monday–Sunday cycle (Gregorian calendar)

The date is converted to a continuous count of days on the proleptic Gregorian calendar, and the remainder of that count within a seven-day cycle gives the weekday. Because the day index already contains every leap day, no separate correction is needed, and the answer is exact for dates centuries in the past or future. The weekend flag simply checks whether the resulting weekday is Saturday or Sunday, the standard Western non-working days.

Source:ISO 8601 / Gregorian calendar

We review all our tools from time to time to ensure accuracy.

Worked example

Date:2026-07-04

4 July 2026 falls on a Saturday, which the calculator flags as a weekend.

How to use this calculator

1
Enter your values
Enter date.
2
Adjust the options
Fine-tune any options to match your situation.
3
Read your result
Day of the week updates instantly as you type — no button to press.

Frequently asked questions

What day of the week was I born on?

Enter your date of birth and the calculator returns the exact weekday, from Monday to Sunday. It works for any date on the Gregorian calendar, including dates well over a century ago, because it computes from a continuous day count that includes every leap day. This is the same method almanacs use, so the birth-day answer it gives matches historical records for the Gregorian era.

Which days count as the weekend?

The calculator uses Saturday and Sunday as the weekend, following the standard Western working week. Some regions, particularly in the Middle East and parts of Asia, treat Friday and Saturday or Friday and Sunday as the weekend. If your context uses a different convention, read the named weekday and apply your own rule, since the day name itself is universal even where the weekend definition differs.

Does it work for future dates?

Yes. The seven-day cycle and the Gregorian leap-year rules are fully defined into the future, so the weekday for any upcoming date is exact, not an estimate. This makes it reliable for planning events, deadlines and schedules years ahead. The only caveat is that civil calendars could in principle be reformed, but no such change is planned, so future weekdays computed this way are dependable.

Is it accurate for very old dates?

It is accurate on the proleptic Gregorian calendar, which extends today's rules backwards. For dates before a country adopted the Gregorian calendar in 1582 or later, historical records may have used the Julian calendar, so the weekday people recorded at the time could differ. For modern dates in any country that has adopted the Gregorian system, the result matches the calendar in everyday use.

Why does the weekday matter for deadlines?

Many rules move a due date that lands on a weekend to the next business day, so knowing the weekday tells you whether an adjustment applies. A tax payment, court filing or invoice due on a Saturday is often effectively due the following Monday. Checking the weekday first lets you plan around these rollovers instead of being caught out by a deadline that quietly shifts.