Find what day of the week any date fell or falls on, including historical dates in the old Julian calendar. Fast, free, and built for simple browser-based workflows.
Calculated in this browser tab. The date you pick is not sent anywhere.
Day of the week
Pick a date, or try the example.
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Day of the Week Calculator is a free online tool that tells you what day of the week any date fell or falls on, from the year 1 to the year 9999. Enter a date and it shows the weekday instantly, along with the ISO week number, the day of the year, and whether that year is a leap year.
It earns its keep whenever a record only gives you a date and you need the weekday: checking what day a contract clause or deadline falls on, settling "what day was I born on", confirming a historical date everyone assumes fell on a different day, or seeing how many of the next ten years a recurring date lands on a weekend. Switching to the Julian (old style) calendar covers dates as they were actually recorded before the Gregorian reform, which a Gregorian-only calculator gets wrong.
Everything is calculated inside your browser, and the date you enter is never uploaded to a server or stored anywhere. That makes it safe to look up a birth date, a confidential contract date, or any other date you would rather not type into a site you do not control.
Pick a date, or click Today. For a record written in the old-style calendar, switch to Julian (old style) first in More options, then type the date into the text field that appears.
More options lets you pick the calendar (Gregorian by default) and how many years the years table covers (5, 10 or 20).
Click Find the Day, or press Ctrl+Enter from either field. The result updates live as you change the date.
The headline shows the weekday. Below it, rows give the long date, ISO date, day of the year, ISO week and leap year status, and a table lists the same date's weekday in future years - each row has its own copy button.
Yes! All our tools are 100% free to use with no hidden costs, no registration required, and no credit card needed.
Absolutely. All tools run entirely in your browser (client-side). Your data never leaves your device and is not sent to our servers.
Yes, once the page is loaded, the tool will continue to work even if you lose internet connection since it runs in your browser.
Yes! All our tools are free for both personal and commercial use.
Enter the date, or click Today, and the weekday appears immediately as the headline. The rows below it add the long date, the ISO week number, the day of the year and whether that year is a leap year.
Gregorian is the modern calendar used worldwide today, extended backward for dates before it existed. Julian (old style) is the calendar actually in use before the Gregorian reform of 1582 (and later in some countries), with its own, slightly different leap-year rule. Pick Julian when you are working from a record that was dated in that calendar at the time.
Yes. Enter your date of birth in Gregorian mode (the default for any date from 1582 onward) and the weekday appears as the headline, with the exact date's ISO week and day of the year underneath it.
Yes, using the modern calendar extended backward by default, with a note saying so. For a date that was actually recorded in the Julian calendar at the time - common for historical dates before 1582, or before 1752 in Britain and its colonies - switch to Julian (old style) instead for the weekday as it would have been understood then.
The same month and day in each of the next 5, 10 or 20 years (your choice, in More options), with the weekday of each. For a Feb 29 date, it lists the next leap years instead, since Feb 29 does not exist in every year.
Most likely because the two are using different calendars. A history book usually gives the weekday as it was recorded at the time, in the Julian calendar; this tool's Gregorian mode instead extends the modern calendar backward, which can land on a different weekday for the same event. Switch to Julian (old style) to match the historical record.
It is the date's week number under the ISO 8601 standard, where weeks start on Monday and week 1 is the week containing the year's first Thursday, shown in the form 2026-W40. It is only shown in Gregorian mode, since ISO weeks are a modern-calendar concept.
Yes, in Julian mode. 1700 is a leap year under the Julian calendar's simpler every-4-years rule but not under the Gregorian rule, so a Gregorian date picker will not accept Feb 29, 1700; switching to Julian (old style) and typing it into the text field works, and shows the Gregorian equivalent date alongside it.
No. A date's weekday is the same everywhere in the world, so changing time zones never changes it. Only the Today button, which reads the current date from your device's clock, depends on your local time zone.