The formula
Write your birth month as a number, where January is 1 and December is 12. Then work out:
55 − (2 × month + day)
You’ll get a number from 1 to 52. That number is your card’s place in the deck.
Turning the number into a card
Count through the deck in this suit order, with each suit running Ace, 2 to 10, Jack, Queen, King:
- Hearts: 1 to 13
- Clubs: 14 to 26
- Diamonds: 27 to 39
- Spades: 40 to 52
Worked examples
- 10 March: 55 − (2 × 3 + 10) = 39. That’s the King of Diamonds.
- 1 January: 55 − (2 × 1 + 1) = 52. That’s the King of Spades.
- 14 February: 55 − (2 × 2 + 14) = 37. That’s the Jack of Diamonds.
- 5 November: 55 − (2 × 11 + 5) = 28. That’s the Two of Diamonds.
The Joker and 29 February
31 December is the only birthday that gives 0, so it takes the Joker. 29 February works like any other date: 55 − (2 × 2 + 29) = 22, the Nine of Clubs.
Why do some cards have more birthdays?
Each card’s number can only be reached by certain month and day combinations. Cards in the middle of the deck can be reached by many months, while cards near the ends can’t. Across the deck, the Ace of Hearts, the Two of Hearts, the Queen of Spades and the King of Spades each have the fewest birthdays, with 1, while the Nine of Clubs, the Ten of Clubs, the Jack of Clubs, the Queen of Clubs, the King of Clubs, the Ace of Diamonds, the Two of Diamonds, the Three of Diamonds and the Four of Diamonds each have the most, with 12.
You can see every date for every card on the birth card by birthday page, or skip the maths and use the free birth card calculator.
See your own Cardology year. Enter your birthday to find your card, your planet year and the seven 52-day periods of your year, with a printable PDF.
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