Day of the Week Calculator

Find what day of the week any date falls on, from the year 1000 to 9999. The day of the week calculator also shows that date's weekday in each of the next 10 years.

Updated
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Day of the week
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How to use the Day of the Week Calculator

  1. Choose a Date. It starts at today.
  2. Change the date to any day in the past or future.
  3. Press Calculate. The weekday appears with the full date, and a table shows the weekday of that date in each of the next 10 years.

How it works

The calculator counts the days between your date and January 1, 1970, a Thursday, and takes the remainder after dividing by 7:

weekday = (days since 1970-01-01 + 4) mod 7   (0 = Sunday)

Days are counted in the proleptic Gregorian calendar, with leap years included.

Examples

  • January 1, 2000 was a Saturday.
  • July 20, 1969, the first Moon landing, was a Sunday.
  • Christmas 2026 falls on a Friday.

Why dates move one or two weekdays each year

365 days is 52 weeks and 1 day, so a date usually falls one weekday later the next year. After February 29 in a leap year it moves by two. The pattern of weekdays repeats every 400 years.

Limitations

  • Uses the Gregorian calendar for all dates. For dates before 1582, historical records may use the Julian calendar, which differs by several days.
  • A February 29 date is shown as February 28 in years without that day.

Frequently asked questions

What day of the week was I born?

Enter your date of birth and the calculator shows the weekday.

What day was January 1, 2000?

A Saturday.

Does this work for historical dates?

For dates after 1582 in countries using the Gregorian calendar, yes. Earlier records often used the Julian calendar.

Often used together with the Day of the Week Calculator.