Methodology and formulas

The reduction rule

Many tarot methods end with a number that has to become one of the 22 Major Arcana cards. We use one rule everywhere: while the number is greater than 22, replace it with the sum of its digits. A result of 22 is The Fool, which is printed as 0 on the card.

Some sites subtract 22 instead, which can give a different card for the same birthday. Our guide on why arcana calculators give different results compares the two.

Arcana number

Your arcana number is the main result of the arcana calculator. Write the birth date as eight digits in month, day, year order (MMDDYYYY), add every digit, then apply the reduction rule. Writing the day first gives the same total, since only the digits matter.

Worked example: March 15, 1990 → 0 + 3 + 1 + 5 + 1 + 9 + 9 + 0 = 28 → 2 + 8 = 10, the Wheel of Fortune.

The optional numerology root setting keeps reducing to a single digit but stops at 11 or 22. For March 15, 1990 that gives 28 → 10 → 1, The Magician.

Tarot birth cards (Mary K. Greer’s method)

The tarot birth card calculator adds the month, day and year as whole numbers, then adds the digits of that total. Reduced to 22 or less, the result is your personality card. Reduced to a single digit, it’s your soul card.

Your hidden factor cards are the other cards that share your soul number. These families are called constellations: 1-10-19, 2-11-20, 3-12-21, 4-13-22, 5-14, 6-15, 7-16, 8-17 and 9-18.

Worked examples: April 13, 1975 → 4 + 13 + 1975 = 1992 → 21 and 3. January 4, 1985 → 1990 → 19, 10 and 1. January 7, 1985 → 1993 → 22 and 4.

We also show the four-part method for comparison: month + day + the first two digits of the year + the last two. March 16, 1989 → 3 + 16 + 19 + 89 = 127 → 10.

Year, month and day cards

• Your year card is birth month + birth day + the year you want, with the digits of the total added and reduced. It runs for the calendar year, from January 1. Example: an April 15 birthday in 2026 → 4 + 15 + 2026 = 2045 → 11, Justice. Try it in the tarot year card calculator.
• The collective year card is the digit sum of the year itself, the card everyone shares. 2026 → 10, the Wheel of Fortune; 2027 → 11, Justice.
• Your month card is your year card + the month number, reduced. All twelve are shown in the tarot month card calculator.
• Your personal day card is your month card + the day of the month, reduced. The collective day card is the arcana number of today’s date. Both are on the daily arcana page.

For comparison, results also show two variants used elsewhere: adding all the digits of the date, and subtracting 22 from month + day + the year’s digit sum.

Destiny matrix (22‑arcana method)

The destiny matrix calculator builds an octagon of points from your birth date. Every value below is reduced with the same rule. The matrix uses Marseille numbering, so 8 is Justice, 11 is Strength and 22 is The Fool.

Worked examples: June 23, 1992 → A 5, B 6, C 21, D 5, E 10, karmic tail 15-20-5. March 15, 1990 → A 15, B 3, C 19, D 10, E 11, karmic tail 21-4-10. December 29, 1990 → A 11, B 12, C 19, D 6, E 12.

We ran every date from 1900 to 2100 through these formulas: exactly 26 karmic tails can occur.

In the year forecast, your year energy is the value on the age map at or just below your current age (ages 0 to 80, starting at point A). Month energy is the year energy + the month number, reduced. The soulmate point is the relationship entry point, D2.

Numerology numbers

• For the life path, reduce the day, month and year separately (keeping 11 and 22 whole), add them, and reduce again. A total of 11, 22 or 33 stays whole; 33 can only appear when one of the parts was 11 or 22. Try it in the life path number calculator.
• For name numbers, letters take Pythagorean values (A, J, S = 1 through I, R = 9). Expression uses every letter, soul urge the vowels and personality the consonants, each reduced to 1–9 while keeping 11, 22 and 33. All six core numbers are in the numerology calculator.
• A, E, I, O and U are vowels. Y counts as a consonant unless a name has no other vowel (Lynn, Glyn), when it counts as the vowel. A name with no vowels at all has no soul urge number, and one made only of vowels has no personality number.
• The birthday number is the day of birth, reduced. The maturity number is life path + expression, reduced.
• Your personal year is the digits of your birth month + birth day + the current year, reduced to 1–9 (each personal year number has its own meaning). Personal month adds the calendar month; personal day adds the day of the month. Try it in the personal year calculator.
• Karmic debt is flagged when 13, 14, 16 or 19 appears before reduction, as the birth day, the life path total or a name total. Checked by the karmic debt calculator.

Compatibility

The couple card in the arcana compatibility calculator is the first person’s arcana number + the second person’s, reduced. The element match compares the Golden Dawn elements of the two cards.

Companion Minor Arcana card

This is our own name-based pairing, not a traditional rule. Add up the values of every letter in the name, subtract 1, and divide by 56; the remainder gives a position in the deck order Wands, Cups, Swords, Pentacles (Ace to King each).

Worked example: “Alex Morgan” totals 47. (47 − 1) ÷ 56 leaves 46, the 47th card in that order: the Five of Pentacles.

Card draws and readings

• Draw tools shuffle the full 78-card deck with a Fisher–Yates shuffle, and each card has a 30% chance of appearing reversed.
• The daily card uses a repeatable seed made from today’s date and your birthday, so your card stays the same all day.
• Yes or no and three-card readings use your browser’s cryptographic random number generator. For yes or no, each card has a set answer upright and reversed, the same one shown on its card page. Upright cards keep their traditional lean; a reversal usually weakens or delays it, though a few cards turn the other way (the Devil reversed is a yes to breaking free).
• The focus card is one card from the full deck, shuffled with a seed made from your question, today’s date and your birth date, so the same question gives the same card on the same day.
• All 231 pairs of Major Arcana cards have their own written meanings in tarot combinations. Other pairs are read by elemental dignity: the same element strengthens, Fire with Air and Water with Earth support, Fire with Water and Air with Earth oppose, and other mixes stay neutral.
• Spread summaries count the Major Arcana, the leading suit, any missing suit, repeated numbers, court cards and reversals.

Angel numbers and portal days

Your birthday angel number is your life path digit repeated three times (11 → 1111, 22 → 2222). A personal portal card is your arcana number + the portal number (11 for 11:11, for example), reduced to 22 or less. The dates of each portal day are in the spiritual calendar.

Card numbering

Card meaning pages use Rider-Waite-Smith numbering, with Strength as 8 and Justice as 11. Destiny matrix energy pages use Marseille numbering, where the two are swapped. The Fool is 0 on the card and 22 in every sum.

Sources and corrections

These methods come from Mary K. Greer’s Tarot for Your Self (birth, year and constellation cards), Natalia Ladini’s Matrix of Destiny method (the matrix and karmic tail), the Golden Dawn correspondences (card elements and astrology) and standard Pythagorean numerology. The full reading list is on the about page, and the editorial policy explains how pages are checked.

If a result looks incorrect, please contact us with the birth date and the page address, and we will review it.

Methodology version 1.2, updated October 2026.