Compatibility Calculator
Numerology's Take on Compatibility
Long before dating apps had matching algorithms, numerologists were reducing birth dates to a single digit — the "life path number" — and comparing them between two people. This calculator automates that tradition exactly: it sums the digits of each birthdate, reduces the result, and scores the pair by how close their life path numbers land.
The Formula
Life Path Number = digits of birthdate (YYYYMMDD) summed, then repeatedly
reduced to a single digit — unless the sum is 11, 22, or 33 (kept as "master numbers")
Difference = |Life Path 1 − Life Path 2|
Compatibility Score = 100 − (Difference × 8), clamped between 10 and 100
reduced to a single digit — unless the sum is 11, 22, or 33 (kept as "master numbers")
Difference = |Life Path 1 − Life Path 2|
Compatibility Score = 100 − (Difference × 8), clamped between 10 and 100
Worked Examples
| Birthdate 1 | Life Path | Birthdate 2 | Life Path | Difference | Score |
|---|---|---|---|---|---|
| 1990-05-15 | 3 | 1988-11-23 | 33 (master) | 30 | 10% |
| 1995-07-04 | 8 | 1995-07-04 | 8 | 0 | 100% |
| 2000-01-01 | 4 | 1975-12-25 | 5 | 1 | 92% |
A master number (11, 22, or 33) is never reduced further, so it can sit numerically far from single-digit life paths — producing a low score even when a numerologist would call the pairing significant. That's a property of the reduction rule, not a bug.
Where This Gets Used
- Icebreakers and party games — quick to run for a group, since it only needs two birth dates.
- Numerology enthusiasts — comparing life path numbers is one of the first things a numerology reading covers for a couple.
- Curiosity about a new date — a fast way to generate a talking point before a first date, without reading a full chart.
Note: Numerology-based compatibility is a centuries-old tradition, not a scientifically validated predictor of relationship success. Treat the score as entertainment.
How to Use This Calculator
- Enter Your Birthdate.
- Enter Their Birthdate.
- Select Calculate to see each life path number and the resulting compatibility percentage.
Related Calculations
See the Love Calculator for a name-based version of the same idea, or the Soulmate Compatibility Calculator for a zodiac-sign approach.