Day of the Week of Birth
Instantly find out what day of the week corresponds to your birth date (or any other date), and the next year when your birthday falls on that same day. Calculated locally, in your browser.
How It Works
Many people don't know the exact weekday of their birth, simply because they never thought to check at the right time. This tool calculates that day directly from your birth date using the browser's internal calendar, with no database or external service, then finds the next year when the birthday falls on the same weekday.
Why doesn't my birthday fall on the same day every year?
A calendar year has 365 days, which is not a multiple of 7: each year, the birthday moves forward by one weekday (or two if a leap year occurs in between, due to the extra day of February 29).
Does the calculation work for very old dates?
Yes, as long as the date stays within the range handled by JavaScript's Date object (several hundred thousand years in the past and future), the weekday is calculated correctly according to the current Gregorian calendar, including for very old birth dates.
Your birth date stays in your browser: it is neither saved nor sent to a server.