What Is Compatibility by Date of Birth
Compatibility by date of birth is one of the most popular practical applications of numerology. According to tradition, the birth dates of two people can be compared to assess how well suited the partners are to each other: how their characters, shared household, and common goals work together. An important caveat from the start: all interpretations below are given as "according to tradition," not as established facts. Numerology is not a science but a popular esoteric practice; for its scientific status, see the end of the article.
It is important to distinguish numerological compatibility from astrological compatibility from the outset. Astrology compares horoscopes: planetary positions, zodiac signs, and constructs synastry — the overlay of partners' natal charts. Numerology, on the other hand, works with numbers: the date of birth (life path number, birth number) and the name (name number, in popular terminology the destiny number). The calculator does not need the time or place of birth — only two dates and, optionally, names. Therefore, "compatibility by date of birth" in the numerological sense has nothing to do with "zodiac sign compatibility," "destiny matrix," or tarot arcana: these are independent systems and should not be mixed.
Compatibility Calculator by Date of Birth
The compatibility calculator for two people operates on a separate page: two birth dates are entered along with "Male / Female" fields (queries like "compatibility between a man and a woman by date of birth" are among the most frequent in this topic). The output is a compatibility percentage and interpretation according to the methods described below. To proceed to the calculation: compatibility calculator by date of birth and name.
An important caveat: percentages are a calculator tool, a simplification for visual clarity. In the original sources — in Cheiro, in Sepharial, in the available portion of Aleksandrov's method — there are no compatibility percentages anywhere; details in the "Controversial Points" section.
How Compatibility Is Calculated
In popular practice, two basic approaches have emerged, both based on one principle — reducing numbers to a single digit. A detailed guide with examples is given in the article "How to Calculate a Life Path Number"; here is a brief overview.
By life path number (full date reduction). The day, month, and year of birth are added digit by digit until a number from 1 to 9 is obtained. Example: date 15.08.1990 → 1 + 5 + 0 + 8 + 1 + 9 + 9 + 0 = 33 → 3 + 3 = 6. If at an intermediate step 11, 22, or 33 appears, the schools diverge: according to Cheiro they are reduced (11 → 2, 22 → 4, 33 → 6), in modern practice they are often retained as master numbers. This approach is Western and is also used in Russian-language calculators.
By birth number (day of the month). In Cheiro, the "birth number" is determined by the day of the month: those born on the 1st, 10th, 19th, or 28th are "people of number 1"; those born on the 2nd, 11th, 20th, or 29th are "people of number 2," and so on. Compatibility in Cheiro is described primarily for these birth numbers and their "series."
By name (name/destiny number). Letters of the name are assigned values from 1 to 9 according to a correspondence table, and the sum is reduced to a single digit. It is important here to distinguish between tables: the Pythagorean (A=1, B=2, …, I=9, then the cycle repeats) and the Chaldean used by Cheiro, in which the number 9 is absent because 9 is "the name of God." The same letter yields different numbers in different systems, so the school used should always be specified in the calculation.
Compatibility by Life Paths: Number Pair Table by Cheiro
The primary documented body of work on number compatibility is provided by Cheiro in "Book of Numbers" (1926, public domain). Compatibility is described qualitatively — as "affinity," "harmonious vibration," "interchangeable numbers," and "series" of numbers (e.g., 1—4 and 2—7). Cheiro has no percentages. A summary of pairs actually found in verified sources is given in the table.
Pair | Nature of Connection (according to Cheiro) |
|---|---|
1 — 1 | People of the same series are "naturally sympathetic to each other" |
1 — 2 | Opposite in character, but vibrations are harmonious — "good combinations" |
1 — 4 | "Sympathetic and harmonious vibration"; 1 is always associated with 4 (written as 1—4 or 4—1); the four must not be suppressed — it needs to retain its individuality |
1 — 7 | People of number 1 get along well with those born under 2, 4, and 7 |
Series 1—4 ↔ 2—7 | "Affinity and attraction" between the Sun-Uranus series (1, 4, 10, 13, 19, 22, 28, 31) and the Moon-Neptune series (2, 7, 11, 16, 20, 25, 29); strengthened if people were born in the "House of the Moon" (June 20–21 – July 20–27) or "House of the Sun" (July 21 – August 20–27) |
2 — 4 | Interchangeable number for two is 4 (along with 1 and 7); no separate pair analysis |
2 — 7 | "Twos" vibrate, to a lesser extent, with "sevens"; number 7 has a secondary number 2 (Moon), sevens get along well with Moon numbers 2, 11, 20, 29 |
3 — 3 | "More in harmony with those born under their own number"; according to Sepharial — "consonant relationships" |
3 — 6, 3 — 9 | "People of 3, 6, 9 are sympathetic to each other"; numbers are interchangeable |
5 — any | "5 is the only number that can combine or harmonize with any other"; best friends are those born under the 5 series: 5, 14, 23 |
6 — 3, 6 — 9 | 6 makes more friends than any other class (except 5), especially among vibrations 3, 6, 9; 3, 6, and 9 are interchangeable with 6 |
7 — 2 (series 2, 11, 20, 29) | 7 "gets along well and easily makes friends" among Moon numbers |
8 — 4 | 4 is an interchangeable number for 8 (lucky numbers 4, 13, 22, 31); but 4+8 as "key numbers" are unlucky in attachments |
9 — 3, 9 — 6, 9 — 9 | People of 9 get along well with those born in the 3, 6, 9 series (3, 6, 9, 12, 15, 18, 21, 24, 27, 30 dates); 3 and 6 are interchangeable with 9 |
11 | No separate compatibility table; 11 belongs to the 2—7 series and falls under the "affinity" of the 1—4 and 2—7 series |
22 | No tables; according to Cheiro 22 reduces to 4 — it is correct to speak of the compatibility of 4, not 22 |
33 | No data from any school; according to Cheiro 33 = 24 = 6, "has no independent force" |
An honest caveat: pairs that do not have separate descriptions in the table (e.g., 1—3, 2—8, 4—9, 6—8, 7—9) are not found in open sources — neither in Cheiro, nor in Sepharial, nor in the number cards. The only exception is the universal harmony of number 5, which according to Cheiro combines with any number. We do not fill gaps with assumptions. Furthermore, "series affinity" is a characteristic of birth number vibrations, not an individual prediction for a specific pair: any conclusions about specific relationships are an interpretation by a practitioner, not a quote from the source.
Other Schools and Traditions
In addition to Cheiro, several other systems exist in open sources. They should be distinguished and not mixed.
Sepharial, "The Kabala of Numbers" (1911). An occult system of "sympathetic, consonant, and dissonant" relationships between numbers. In Sepharial's system: number 3 "is in sympathetic vibrational relationships" with number 6 and "in consonant relationships" with its own number; 3 "would be in dissonant relationships" with 5; 9 and 5 — "in relationships of kinship/sympathy"; 3 (growth, optimism) and 8 (decline, destruction) — "in opposition and mutually destructive." This is a separate system from the early 20th century and does not coincide with Cheiro: for example, in Cheiro 5 harmonizes with any number, while in Sepharial 3 and 5 are dissonant.
Nine Star Ki (Chinese feng shui tradition). Number-"stars" are grouped by five elements: 1 — water (standalone); 2, 5, 8 — earth; 3, 4 — wood; 6, 7 — metal; 9 — fire. Compatibility of stars and groups "generally follows the cycles of the five elements — support versus control" (for example, fire is fueled by wood). This is a feng shui context, not Chaldean numerology. More on the school in the article on Chinese numerology.
Vedic practice. "Soul number compatibility" — comparison of partners' numbers; according to tradition, "harmonious" number pairs indicate compatibility of characters. There is no encyclopedic documentation: this is a popular practice of the 20th–21st centuries, and no specific pair tables have been found in open sources. More in the article on Vedic numerology.
Honest note on gaps. In Kabbalah/gematria, "Mayan numerology," and the classical Pythagorean school, no partner compatibility tables have been found in open sources. Gematria connects words with equal numerical sums of letters — this has not been applied to human compatibility in available sources. The Pythagoreans had only symbolic analogies: Agrippa (Book II of "Occult Philosophy") relates that the Pythagoreans called 5 "the number of marriage" and justice (5 is the midpoint of the number 10: 9+1, 8+2, 7+3, 6+4; it consists of the first even and the first odd number), 2 — "the number of charity and mutual love, marriage and society," 6 — the number of "generation and marriage." This is the symbolism of numbers, not a method for calculating compatibility between two people — do not confuse with a popular calculator.
Compatibility by Pythagorean Square
Compatibility is a popular application of the Pythagorean Square (psychomatrix), a modern Russian-language method that in popular tradition is associated with the name of A. F. Aleksandrov. The approach is as follows: psychomatrixes of both partners (3×3 tables by date of birth) are constructed, then key lines are compared: "family" (2, 5, 8), "stability" (3, 6, 9), "determination" (1, 4, 7), as well as strong and empty cells.
Conclusions are drawn "according to tradition": for example, the alignment of strong family and stability lines indicates a strong domestic union, while empty cells of one partner may be "complemented" by strong cells of the other. Important caveats: the exact method of Aleksandrov is set out in his books, which are not freely accessible, so only the general outline is provided here without "exact formulas"; there are no percentages in the method. The calculation and interpretation of the square are described in a separate article on the Pythagorean Square.
Compatibility by Name and Destiny Number
In Cheiro there are two "numbers": the birth number (by date) and the name number (by name; in modern terminology often called the destiny or expression number). Cheiro himself recommended aligning these numbers: "if possible, make them match; the vibrations will be in harmony." For the name, he takes "the name most commonly used" — usually the Christian name plus surname.
Name compatibility is a popular modern service: according to tradition, the names' numbers of partners are compared using the same logic as birth date numbers. There are no percentages in the original sources here either. Furthermore, calculating Russian names requires transliteration, which is not described in open encyclopedic sources, and the Chaldean table of Cheiro (without the number 9) and the Pythagorean table (1–9) yield different numbers for the same name — always specify the system.
Controversial Points: Where Sources Honestly Diverge
The method is modern and popular, not ancient. There is no specific "compatibility calculation method" in ancient, medieval, or encyclopedic sources: among the Pythagoreans — symbolic analogies ("5 = marriage"), in Cheiro and Sepharial — occult systems of the early 20th century, in Wikipedia the topic of partner compatibility is not covered at all. The popular "compatibility calculator by date of birth" is a construct of the 20th–21st centuries.
Compatibility percentages are a marketing device without an original source. Neither Cheiro, nor Sepharial, nor the available portion of Aleksandrov's method provide percentages: Cheiro offers qualitative characteristics ("affinity," "harmonious vibration"), Sepharial offers qualitative relationships (consonance/dissonance), the Pythagorean Square uses comparison of lines and cells. The percentage on the website is a calculator simplification for visual clarity.
Master numbers 11, 22, 33. According to Cheiro they are reduced (11 → 2, 22 → 4, 33 = 24 → 6); in modern practice they are often retained as independent values. When calculating compatibility this produces different pairs — we do not smooth over the discrepancy, we show both schemes and always indicate which school was used.
Sepharial contradicts Cheiro. In Sepharial 3↔5 is dissonance, 9↔5 is sympathy; in Cheiro 5 harmonizes with any number, including 3. The systems cannot be mixed in one table without noting the school.
4+8: two contexts within one school. In Cheiro there is both "affinity" (4 is an interchangeable number for 8) and an "unlucky combination" (4+8 as "key numbers" are unlucky in attachments). These are different contexts: series compatibility and life "key numbers."
Scientific status. From a scientific perspective, numerology is classified as superstition and pseudoscience: numbers in themselves do not affect a person's life. Two tests of numerological methods have been conducted, both yielding negative results: in the United Kingdom (1993) and in Israel (2012; a professional numerologist and 200 participants, the experiment was repeated twice) — predictions were no different from random guessing.
Disclaimer
All material on this page is for entertainment and educational purposes and does not constitute medical, psychological, or financial advice. All interpretations are given as "according to tradition," not as established facts. When making important life decisions, consult qualified professionals.
See Also
- Pythagorean Square — psychomatrix calculation by date of birth
- Psychomatrix — Aleksandrov's method: terminology and features
- How to Calculate a Life Path Number — guide with examples
- Compatibility Calculator — compatibility by date of birth and name online
- History of Numerology — from the Pythagoreans to modern schools
- Pythagorean, Chaldean, Vedic, and Chinese systems — articles on schools
- Number 1, Number 2, Number 3, Number 4, Number 5, Number 6, Number 7, Number 8, Number 9, 11, 22, 33 — general number meanings
- Glossary — numerology terms