Day of the Week Calculator

Find out what day of the week you were born, and what day you turned or will turn 18, 30 and 50.

Day of the week you were born
Friday
June 15, 1990
Turned 18 on a
Turns 50 on a

How to use the calculator

  1. Choose the birth date.
  2. The calculator automatically shows what day of the week the date fell on.
  3. Also see what day of the week the 18th and 50th birthday falls or fell on.

How the weekday is calculated

The calendar follows a fixed, predictable pattern: a standard Gregorian calendar repeats its weekday pattern at regular intervals, adjusted for leap years every four years (with a few exceptions at century marks). This makes it possible to calculate exactly what day of the week any date falls on, without counting manually.

Your browser uses built-in date functions that handle leap years and the calendar pattern automatically and correctly.

The calculator uses the same method to find the weekday for the date you turned or will turn 18 and 50 — it simply creates a new date with the same month and day, but with the birth year plus 18 or 50, and finds the weekday for that date.

Frequently asked questions

Why is it possible to calculate the weekday for a date decades in the future or past?

The Gregorian calendar follows a fixed mathematical pattern with 365 days in common years and 366 in leap years (every four years, with a few exceptions at century marks). This pattern means the weekday for any date can be calculated precisely, no matter how far forward or back in time it is.

Does this calculator work for dates before the calendar reform (before 1582)?

No. The calculator assumes today's Gregorian calendar, which was introduced in 1582 and later adopted in many countries. It's not intended for historical dates from before the switch to the Gregorian calendar.

Can I use this to find the weekday for occasions other than a birthday?

Yes. The calculator finds the weekday for any date you enter, so you can use it for anniversaries, jubilees, or any other date you're curious about.