Pythagorean vs Chaldean Numerology: The Two Systems Compared
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Pythagorean and Chaldean numerology are two ways of turning letters into numbers: the Pythagorean chart gives letters the values 1 to 9 in alphabetical order, while the Chaldean chart uses only 1 to 8, assigns them by sound and leaves 9 without a letter. Soul Aura uses the Pythagorean system, in its free calculators and in its reports.
What this page is: a side-by-side comparison of the two letter systems, with the same invented names calculated both ways. The Pythagorean figures come from the engine that writes Soul Aura reports; the Chaldean figures come from a short script using the table shown below. What it is not: a ruling on which system is correct, a forecast or professional advice. Neither system is scientifically validated; Soul Aura uses numerology as a structured tool for self-reflection, not fortune-telling.
By the Soul Aura editorial team. Calculation notes are on the method page. Last updated 2026-10-10.
The two letter tables side by side
| Letter | Pythagorean | Chaldean | Letter | Pythagorean | Chaldean |
|---|---|---|---|---|---|
| A | 1 | 1 | N | 5 | 5 |
| B | 2 | 2 | O | 6 | 7 |
| C | 3 | 3 | P | 7 | 8 |
| D | 4 | 4 | Q | 8 | 1 |
| E | 5 | 5 | R | 9 | 2 |
| F | 6 | 8 | S | 1 | 3 |
| G | 7 | 3 | T | 2 | 4 |
| H | 8 | 5 | U | 3 | 6 |
| I | 9 | 1 | V | 4 | 6 |
| J | 1 | 1 | W | 5 | 6 |
| K | 2 | 2 | X | 6 | 5 |
| L | 3 | 3 | Y | 7 | 1 |
| M | 4 | 4 | Z | 8 | 7 |
Only 10 of the 26 letters carry the same value in both systems: A, B, C, D, E, J, K, L, M and N. The other 16 differ, so the totals of a name part company before any reduction takes place. The Chaldean table is the version most often published; a few sources move individual letters, so a different book may disagree with it on one or two.
Why the same name gives different numbers
- Different letter values. The Pythagorean chart simply counts through the alphabet and repeats. The Chaldean chart is described as assigning values by the sound and vibration of each letter, so its values do not follow the alphabet: F is 8 and G is 3.
- The number 9. Chaldean sources hold 9 apart from the letters and describe it as sacred, so it can appear only as a total, never as a letter value.
- Compound numbers. Chaldean readers commonly look at the two-digit total, usually between 10 and 52, before reducing it. Soul Aura's engine records the raw total and uses it to attach the 13/4, 14/5, 16/7 and 19/1 labels.
- Which name. Many Chaldean sources read the name a person is known by, while Pythagorean readings, Soul Aura's included, start from the full birth name.
- Master Numbers. Soul Aura keeps 11, 22 and 33 as they are in its name numbers. Practice among other writers varies, so the same total can be read as an 11 or as a 2.
One name, both systems: Calla Hartwell
| Letter | C | A | L | L | A | H | A | R | T | W | E | L | L | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pythagorean | 3 | 1 | 3 | 3 | 1 | 8 | 1 | 9 | 2 | 5 | 5 | 3 | 3 | 47 |
| Chaldean | 3 | 1 | 3 | 3 | 1 | 5 | 1 | 2 | 4 | 6 | 5 | 3 | 3 | 40 |
The Pythagorean letters add to 47, which the engine keeps as the Master Number 11 (its root is 2). The Chaldean letters add to 40, which reduces to 4. One name, two answers, and neither is a mistake.
| Name | Pythagorean total (engine) | Chaldean total, single digit | Same single digit? |
|---|---|---|---|
| Calla Hartwell | 47 → 11 (Master Number kept) | 40 → 4 | No |
| Idris Kemper | 64 → 1 | 37 → 1 | Yes |
| Linnea Oakhurst | 60 → 6 | 50 → 5 | No |
Across 750 invented names (30 first names combined with 25 surnames), the two systems gave the same single digit for 80, which is 10.7%. That is close to one in nine, the share that two unrelated digits would match by coincidence. The overlap between the systems is therefore small enough that a result from one says little about the other.
How to compare the two fairly with your own name
- Write the name exactly once, in one spelling, and use it for both calculations.
- Add the whole name in each system and keep the raw total, not only the single digit.
- Note the compound number as well: in the example above a Chaldean reader would look at 40 before 4.
- Compare the descriptions of both digits and see which, if either, gives you something to reflect on. Neither is a verdict.
Where each system comes from, and what is not known
The Pythagorean label is borrowed from the Greek philosopher, but the chart in use today is modern. A review of Underwood Dudley's 1997 book Numerology, or What Pythagoras Wrought credits Mrs L. Dow Balliett of Atlantic City, New Jersey, with virtually inventing modern numerology around 1900. That is one reviewer's account, not settled history.
Popular accounts attribute the Chaldean system to ancient Mesopotamia and credit the writer Cheiro (Count Louis Hamon) with popularising it in the early twentieth century. Whether the system he taught is genuinely Babylonian or a later synthesis is debated, and the specific letter values cannot be traced to a surviving Babylonian text. Treat the age of either system as unproven.
Which system Soul Aura uses
Soul Aura uses the Pythagorean system. Every letter-based number in its free calculators and paid reports, including Expression, Soul Urge and Personality, is calculated from the Pythagorean chart, with the Y rule and the Master Number rules set out on the name numerology calculator page. The Chaldean table on this page is shown for comparison only. If you hold a Chaldean reading from elsewhere, expect the numbers here to differ; that is the convention at work, not an error on either side.
The choice is a convention, not a claim that one system is truer. The Pythagorean chart is widely published, uses one repeating cycle of 1 to 9 and lets any result be checked by hand from a single table.
Honest limits
- Neither system has been scientifically validated. Describing one as more accurate has no measurable meaning.
- “The Chaldean number” is not one number, because practitioners differ on the name, the compound numbers and the Master Numbers.
- Any description attached to a number comes from tradition and from how modern authors paraphrase it. Use it as a prompt for reflection and keep only what fits.
Frequently asked questions
Which is more accurate, Pythagorean or Chaldean numerology?
Neither has been scientifically validated, so accuracy cannot be measured for either. They are different conventions. Choose the one whose rules you can follow and whose descriptions you find useful as prompts.
Why does the Chaldean system never give a letter the value 9?
Chaldean sources hold the 9 apart and call it sacred. A 9 can still appear as a total when letter values add up to 18, 27 or 36.
Which system does Soul Aura use?
The Pythagorean system, for every letter-based number in its calculators and reports. The Chaldean table here is for comparison only.
Can I calculate one name in both systems?
Yes, and it is a fair way to see how much depends on convention. Keep each calculation within one table; mixing values from the two charts gives a number that belongs to neither.
Do both systems use the same name?
Not always. Pythagorean readings usually start from the full birth name, as Soul Aura does, while many Chaldean sources use the name a person is commonly known by.
Where to go next
- Run your own name through the Pythagorean chart with the free name numerology calculator, or see all tools on the numerology calculators page.
- See how the outer layer of a name is read in the Personality number guide, and how the date-based number works in the Life Path guide.
- New to the field? What numerology is and is not is the place to start.
If you would like the Pythagorean calculation done across your whole chart, the Soul Aura Personalized Numerology Report uses fixed rules throughout and includes an AI mentor file for follow-up questions. You can read a sample report first.