What is the Milesian or alphabetic numeral system?

It is the classical Greek way of writing numbers using the 24 letters of the alphabet plus three archaic letters. Alpha through theta cover 1 to 9, iota through koppa cover the tens, and rho through sampi cover the hundreds.

What are stigma, koppa and sampi?

They are three letters retained only as numerals: stigma is 6, koppa is 90 and sampi is 900. The Greek alphabet alone has 24 letters, so these three fill the gaps needed to reach 27 numeral symbols for units, tens and hundreds.

How are thousands written?

Thousands from 1000 to 9000 reuse the unit letters alpha to theta but with a keraia mark, a small stroke, placed before and below the letter. This tool prefixes the thousands letters with the lower keraia character.

Is a keraia added to ordinary numerals?

Yes. In manuscripts a keraia, an upper stroke, often follows a numeral to mark it as a number rather than a word. This tool appends the upper keraia to the units-tens-hundreds group.

What is the largest supported number?

The standard alphabetic system reaches 9999 cleanly using the keraia for thousands. Above that, scribes used the myriad letter M with multipliers, which this tool does not encode; it accepts 1 to 9999.

What is the Greek Numeral System Converter?

Encode integers using the Milesian Greek alphabetic numeral system, with the special letters stigma for 6, koppa for 90 and sampi for 900, plus the keraia marks used for numbers above 999. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Greek Numeral System Converter

Name: Greek Numeral System Converter
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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The classical Greek alphabetic, or Milesian, numeral system assigns a value to each letter: alpha to theta for the units, iota to koppa for the tens, and rho to sampi for the hundreds. This converter turns an integer into that notation, including the archaic letters stigma, koppa and sampi.

How it works

The number is split into hundreds, tens and units, and each digit selects a letter from one of three nine-symbol rows:

units    α β γ δ ε ϛ ζ η θ      (1–9, ϛ = stigma = 6)
tens     ι κ λ μ ν ξ ο π ϟ      (10–90, ϟ = koppa = 90)
hundreds ρ σ τ υ φ χ ψ ω ϡ      (100–900, ϡ = sampi = 900)

Thousands (1000–9000) reuse the unit letters but are prefixed with the lower keraia mark ͵. The complete numeral is the thousands group followed by the hundreds-tens-units group, with an upper keraia ʹ appended to mark the whole as a number.

The three archaic letters

The normal 24-letter Greek alphabet does not have enough letters to fill all nine units, all nine tens, and all nine hundreds simultaneously — that requires 27 symbols. Three archaic letters that dropped out of everyday use were kept solely as numerals:

Stigma (ϛ) = 6. It resembles a ligature of sigma and tau and fell out of the written alphabet early, but survived in manuscripts purely to represent six.
Koppa (ϟ) = 90. Originally a letter for a k-sound that Greek no longer needed, koppa was retired from the alphabet but retained as the numeral for ninety.
Sampi (ϡ) = 900. The most obscure of the three, sampi represented a sound that disappeared from Greek very early. Its name may derive from “san pi” (like pi). You will see it only in numeral contexts.

Knowing these three is essential for reading dates and numbers in classical manuscripts, Byzantine texts, and Greek Orthodox service books, where they appear constantly.

Example and tips

241 is written σμαʹ — sigma (200) + mu (40) + alpha (1). The year 1453 (the fall of Constantinople) becomes ͵αυνγʹ: the lower keraia plus alpha for 1000, then upsilon (400), nu (50) and gamma (3). Remember that 6, 90 and 900 use the special letters, so they will look unfamiliar if you only know the modern 24-letter alphabet.

For years in Greek manuscripts you typically see a four-part number like ͵αωπβʹ for 1882. Reading from left to right: lower keraia + alpha (1000), then omega (800), then pi (80), then beta (2). This tool makes that kind of decoding straightforward by showing the component values alongside the combined symbol.

Where you will encounter Greek numerals today

Greek alphabetic numerals remain in active use in several contexts. Greek Orthodox liturgical books use them for chapter and verse numbering, feast day ordering, and year dating in the ecclesiastical calendar. Byzantine musicology uses them to number modes and intervals. Academic editions of classical texts still annotate manuscripts using the original alphabetic numbering when it appears in the source. Typography and design work involving Greek texts sometimes requires the authentic numeral forms. Understanding this system is therefore not purely historical — it is useful for anyone working with Greek religious, musical, or manuscript sources.