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Birthdate to Weekday Calculator




You were born on a: ?

The following steps were taken in calculating the day of the week based on the date entered above

  1. Determine the Century Code
    • Using the year entered above we can determine the century code. See the century code table below!
  2. Determine the Quotient & the Remainder
    1. We first reformat the year to be two digits
      (e.g., 'abcd' becomes 'cd')
    2. Then we divide 'cd' by 12 and we get 'cd'/12 with a remainder of x
  3. Determine how many times 4 goes into the remainder
    • Dividing x by 4 we get x/4 with a remainder of #
  4. Now we determine the Doomsday value based on the month and date
    1. Using the month entered above we can determine the doomsday value for that month using the table below.
    2. Next we take the date value entered above and we subtract the month's doomsday value which gives us a Doomsday value of #
  5. Now we take the sum of the 5 values determined in steps 1-4 and we calculate the remainder after dividing by 7
    1. Sum = Century Code + Quotient + Remainder + Reminder/4 + Doomsday
    2. Sum divided by 7 is # with a remainder of #
  6. Finally, compare your final result from step 5 to the following table to find the corresponding day of the week:
    Sunday Monday Tuesday Wednesday Thursday Friday Saturday
    0 1 2 3 4 5 6

Century Code Table:
5 3 2 0
1-99 100-199
200-299 300-399 400-499 500-599
600-699 700-799 800-899 900-999
1000-1099 1100-1199 1200-1299 1300-1399
1400-1499 1500-1599 1600-1699 1700-1799
1800-1899 1900-1999 2000-2099 2100-2199
2200-2299 2300-2399 2400-2499 2500-2599
2600-2699 2700-2799 2800-2899 2900-2999
3000-3099 3100-3199 3200-3299 3300-3399
3400-3499 3500-3599 3600-3699 3700-3799
3800-3899 3900-3999 4000-4099 4100-4199

Doomsday by Month:
Month Doomsday Value
January
Leap Year Non-Leap Year
4 3
February
Leap Year Non-Leap Year
29 28
March 14
April 4
May 9
June 6
July 11
August 8
September 5
October 10
November 7
December 12