Day of the Week
Find out what day of the week any date falls on — past, present or future. Free and instant: the weekday is calculated right in your browser as you type.
How to use the Day of the Week finder
- Enter a date. Pick the month, day and year of any date between the years 1 and 9999 — a birthday, a wedding, a historical event or a future deadline.
- Read the weekday. The day of the week appears instantly, together with a plain-language sentence like "July 20, 1969 fell on a Sunday".
- Check the extras. The tool also shows how many days away the date is, its day-of-year number, its ISO week number, and whether the year is a leap year. Use the copy button to share the result.
About this tool
This day of the week calculator answers the classic question "what day was I born on?" — and many more. Look up the weekday of any birthday, anniversary or historical event, or plan ahead by checking which weekday a future date such as a wedding, exam, product launch or contract deadline will land on. The calculation uses the Gregorian calendar rules for leap years, so dates repeat their weekday pattern in the familiar 400-year cycle.
Results appear instantly as you change the month, day or year, with no page reloads and no limits. Like every tool on this site, the entire calculation runs locally in your browser — the dates you look up are never uploaded, stored or tracked.
Frequently asked questions
How is the day of the week calculated?
The tool applies the Gregorian calendar's leap-year rules: a leap year is any year divisible by 4, except century years, which must be divisible by 400. Counting days from a known reference weekday then gives the weekday of any date — the same arithmetic behind Zeller's congruence and the Doomsday method.
Is the weekday correct for dates before 1582?
The tool uses the proleptic Gregorian calendar, extending today's calendar backwards. Historical records before the Gregorian reform of October 1582 (later in Britain and its colonies, 1752) were written in the Julian calendar, so a document's date may name a different weekday than the proleptic Gregorian result shown here.
What day of the week was I born on?
Enter your date of birth above and the weekday appears instantly — along with how many days ago that was. This is a popular way to check the "Monday's child" nursery-rhyme verse for a new baby, too.
Do calendars repeat, so the same date falls on the same weekday again?
Yes. A non-leap year's calendar usually repeats after 6 or 11 years, a leap year's after 28 years, and the entire Gregorian calendar repeats exactly every 400 years — which is why any given date's weekday cycle eventually comes back around.