Roman fraction converter
Seven twelfths of an as is S·, the septunx: S for half plus one dot for an uncia. Enter any count from 0 to 12 for the Roman mark, its Latin name and the fraction, useful in Latin and history lessons. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Twelfths
- 7
- Numeral
- S·
- Name
- septunx
- Dots
- 1
- Fraction
- 7/12
This Roman fraction converter maps a whole number of twelfths of a Roman as into the classical uncia notation that used middle dots and the letter S. In Roman commerce and accounting the as was divided into twelve unciae, so fractions of a unit were counted in twelfths rather than in modern decimal places. One twelfth is one uncia and is written as a single middle dot; six twelfths equal a semis and are written S; combinations from seven through eleven append extra dots after S; twelve twelfths make a full as written I; and zero yields an empty numeral. The engine is fully deterministic table logic with no network calls, no sampling, and no date-dependent shortcuts.
What Roman uncia notation is and what you get back
Roman uncia notation is the fractional script that went with the as as a unit of weight and, later, of money. Because an as held twelve unciae, any proper fraction of the unit was expressed as a count of twelfths and written with a small set of marks instead of Arabic numerators and denominators.
A middle dot stands for one uncia; the capital letter S stands for semis, half an as or six unciae; stacking dots after S builds the odd halves from seven to eleven twelfths; and the full unit is the letter I for as.
This converter accepts that twelfths count as an integer from zero through twelve and returns the matching numeral string, the traditional Latin name such as uncia, semis, or deunx, a dots count for the uncia marks actually drawn, flags for whether S or I was used, the ordinary fraction n over twelve, and a short method tag.
Where uncia conversion fits in study, museums, and software
Students meet uncia marks when a Latin or history course covers Roman weights, coin fractions, or primary sources that quote semis and uncia rather than modern decimals. Teachers can pre-generate answer keys for twelfths drills without trusting opaque converter apps that silently switch glyphs or drop the S for half. Epigraphists and museum educators use the same table when labeling displays of as and uncia so visitors see both the count and the classical mark.
Game and narrative designers call the contract when a simulation needs authentic fractional currency strings without inventing modern slash notation. Developers seed deterministic test vectors for localization pipelines, documentary captions, and interactive timelines that must render S with dots exactly as the reference table specifies.
What you can do with it
Latin and history homework
Convert textbook twelfths counts into uncia marks (·, S, S·, I) and check Latin names before exams or worksheets.
Museum labels and epigraphy copy
Generate stable uncia strings for as/uncia displays, catalog cards, and documentary captions that must match classical notation.
FAQ
What does the Roman fraction converter cost?
It is free in your browser on this page.
What input range is accepted?
An integer twelfths count from 0 through 12 inclusive.
How are S and the dots used?
Each middle dot is one uncia (1/12). S is semis (6/12). Values 7–11 are S plus one to five dots. Twelve is I (as); zero is an empty numeral.
Does this convert standard Roman numerals like XIV?
No. It only maps a twelfths count to uncia fractional notation. Use a dedicated Roman numeral tool for whole-number I, V, X notation.
How is seven twelfths written?
Seven twelfths is S·, called septunx: S stands for the semis, six twelfths, and the single dot adds one uncia. The tool also gives the ordinary fraction 7/12 beside the Roman mark.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/fmt/roman-fraction \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"twelfths":7}'const res = await fetch("https://api.kit.forhosting.com/fmt/roman-fraction", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"twelfths": 7
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/fmt/roman-fraction",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"twelfths": 7
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/fmt/roman-fraction", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"twelfths":7}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"twelfths":7}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/fmt/roman-fraction", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"twelfths": 7
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "fmt.roman_fraction",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
min_twelfths | 0 |
max_twelfths | 12 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
What Roman uncia notation is and what the response contains
There is no approximate OCR path and no random sampling of glyphs: the engine either maps a valid integer to the fixed classical table or rejects the input with invalid_input. Rejected cases include missing twelfths, non-integers, non-numeric tokens, and any value strictly below zero or strictly above twelve, because those amounts fall outside the uncia scale of a single as.
How twelfths are read and how the numeral stays reproducible
Optional leading plus signs on integer strings are allowed when they parse as whole numbers; embedded spaces, decimal points, scientific notation, and non-numeric tokens are rejected with a clear message so a bad cell does not become a wrong mark. Zero is valid and returns an empty numeral with the name nulla, which matches the absence of fractional marks on a complete accounting line. Values six through eleven always begin with S and then append zero through five middle dots; values one through five are dots only; twelve is always the single letter I and never twelve dots. The preferred field is twelfths for the integer count of unciae, but aliases n, value, fraction, unciae, text, and input are accepted so spreadsheets, query strings, and typed forms can reuse the same contract. The middle dot character is the Unicode middle dot U plus zero zero B seven, chosen because it is the conventional modern transcription of the uncia mark and stays visible in plain text, JSON, and HTML without custom fonts. Pair the free browser run on this page with the priced API when you need the identical epigraphic string inside an automated pipeline without re-implementing the uncia table yourself.
Where uncia conversion fits in study, museums, and software
On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split — free interactive exploration and a priced, identical API — matches the rest of the KIT tier-A catalog and lets you move from a classroom demo to an automated pipeline without changing the epigraphic result. Pair it with whole-number Roman numeral tools when you need I, V, and X for integers above a single as, and with other format endpoints when you are building a small lab of free, deterministic classical helpers.
Integration use cases
Games, localization, and CI fixtures
Seed reproducible Roman fraction glyphs for simulations, teaching apps, and unit tests without hand-maintaining the 0–12 table.
Technical questions
Which character is used for the uncia mark?
The Unicode middle dot (U+00B7). That is the usual modern transcription of the classical uncia spot in plain text and JSON.