1M / 200C / 30C meaning calculator
The notations 1M, 200C and 30C are three points on Hahnemann's centesimal scale. What follows translates the shorthand, sets out the dilution arithmetic, and places each level in classical prescribing.
30C denotes thirty serial dilutions of one part remedy stock to ninety-nine parts diluent, succussed at each step. 200C extends the same procedure to two hundred steps. 1M is Hahnemann's later notation for one thousand centesimal steps, with M used as the Roman numeral for one thousand. The three values are points on a single scale, not different scales. For the arithmetic behind any centesimal or decimal step, the homeopathic dilution calculator runs the numbers directly; the potency converter handles cross-scale conversions between centesimal, decimal, and LM.
How the three potencies compare
| Potency | Centesimal steps | Implied dilution factor | Classical disposition |
|---|---|---|---|
| 30C | 30 | 10⁻⁶⁰ | Acute and first-aid prescriptions; broad practitioner familiarity |
| 200C | 200 | 10⁻⁴⁰⁰ | Constitutional and chronic-miasm cases; common Kentian potency |
| 1M | 1,000 | 10⁻²⁰⁰⁰ | Single high-dose prescriptions in sensitive constitutional cases |
How practitioners choose between the three
The choice between 30C, 200C and 1M is governed by the case rather than the symptom label. Kent ascends the scale when the simillimum is well established and the patient is sensitive. Boenninghausen's earlier teaching treats 30C as the workhorse for acute prescriptions and reserves higher potencies for chronic-miasm presentations — his original case logic is browsable in the Boenninghausen's Pocket Book online. Vithoulkas adds a sensitivity-assessment step before any 1M prescription, on the grounds that an over-deep dose can prolong an aggravation.
Traditional indications for each level
30C suits acute prescriptions where rapid action is sought, first-aid situations, and cases where the simillimum is still being established. It is the standard teaching potency in most college curricula and is appropriate for patients with no prior high-potency exposure.
200C is the preferred Kentian level for well-confirmed constitutional remedies and for chronic-miasm cases where the simillimum is clearly established. It is routinely used in single-dose prescriptions followed by watchful waiting before repetition.
1M is reserved for deeply sensitive constitutional cases, for long-standing chronic disease with a clear simillimum, and for situations where prior 200C doses have acted well but show diminishing response. Hahnemann sets out the rationale for ascending the scale this way in Organon §270 and in Chronic Diseases.
What the calculation actually returns
For an arbitrary "nC" input, two deterministic values fall out: the step count n and the implied dilution factor 10⁻²ⁿ of the original stock. Modern repertorisation software extends this by storing the prescribed potency against the rubric and surfacing prior-case potency history for the simillimum under review — the classical repertory at similia.io keeps a per-case potency log so the notation question and the prescribing-history question can be carried together inside one workflow.
References
Hahnemann, S. (1842) Organon of the Medical Art, 6th edition, §270.
Hahnemann, S. (1833) Chronic Diseases: their peculiar nature and their homoeopathic cure, 2nd edition.
Boenninghausen, C. von (1846) Therapeutisches Taschenbuch, Münster.
Kent, J. T. (1900) Lectures on Homoeopathic Philosophy, Lancaster, Pa.
Vithoulkas, G. (1980) The Science of Homeopathy, Grove Press, New York.