Find what day of the week any date falls on — past or future. Look up the day for a birthday, historical event, contract date or any date across centuries. Includes the day number and week number.
Type or pick any date — past, present or future. You can enter historical dates (the Battle of Hastings, the signing of the Magna Carta) or future dates (upcoming deadlines, anniversaries). The Gregorian calendar is used for all calculations.
The result shows immediately: the full day name (e.g. Wednesday), the abbreviated day (Wed), the ISO day number (1=Monday through 7=Sunday), the ISO week number of the year, and the day number within the year (1–366).
A small calendar highlights your chosen date in context, showing the full month so you can see surrounding dates, weekends and where the date falls in the week at a glance.
The calculator uses JavaScript built-in Date object, which internally uses the proleptic Gregorian calendar and Unix timestamp arithmetic. For historical dates before 1582 (when the Gregorian calendar was adopted), results are calculated using the proleptic Gregorian calendar extended backwards — which may differ from the Julian calendar actually used at the time.
Enter your exact date of birth and the calculator instantly shows your birth day. Many people are curious about this — it a fun fact for conversation, and some cultures attach significance to birth day names (e.g. the Akan people of Ghana give children names based on the day of the week they were born).
The ISO 8601 standard defines a week as starting on Monday, with the first week of the year (Week 1) being the week containing the first Thursday of January. This means January 1 is sometimes in Week 52 or 53 of the previous year. ISO week numbers are widely used in European business, logistics, manufacturing and project planning.
The day number (also called ordinal date or Julian day number in everyday use) counts from 1 on January 1st to 365 or 366 on December 31st. Day 1 = January 1, Day 32 = February 1, Day 100 = April 10 (approximately). It is useful in astronomy, military scheduling and systems that track annual progress.
Before the Gregorian calendar reform in 1582 (or later in some countries — Russia switched in 1918, Greece in 1923), dates were recorded using the Julian calendar. Our calculator uses the proleptic Gregorian calendar, which may show a different day than period documents recorded. For precise historical research, consult a Julian calendar converter.
Enter any future date — a planned event, contract expiry, product launch or anniversary — and the tool shows the day name instantly. This is useful for checking whether a deadline falls on a weekend, scheduling meetings on specific weekdays, or confirming that an annual event always falls on the same weekday.
Many recurring public holidays are set on specific weekdays — for example, US Thanksgiving is the fourth Thursday of November, and UK bank holidays often fall on Mondays. Our calculator shows the day for any entered date so you can plan around these days when scheduling deadlines and events.
Yes — enter December 25 for any year and the calculator instantly shows the day. Christmas 2025 falls on Thursday, 2026 on Friday, 2027 on Saturday, 2028 on Monday. Planning holiday schedules years in advance is a common use case for this tool.
In a common year, January 1 advances one day of the week compared to the previous year. In a leap year (which has 366 days), January 1 of the following year advances two days. This creates a 28-year cycle in the Gregorian calendar after which the same dates fall on the same days of the week.
Enter the first day of the target month and note the day of the week. Then add the appropriate number of days. For example, to find the 3rd Tuesday of March 2026: March 1 is a Sunday, so the first Tuesday is March 3, the second is March 10, and the third is March 17. Our mini calendar view shows the full month, making this easy to see at a glance.
