Roman Numeral Converter API

Convert a whole number to Roman numerals (1 to 3999, or up to 3,999,999 with vinculum overlines) or Roman numerals to a number. The direction is detected from the input.

POST /api/v1/tools/roman-numeral-converterMCP roman_numeral_converterCalculators

Convert numbers to Roman numerals and back, from 1 to 3,999, with strict checks that explain why forms like IIII, VX or IC are wrong, and a breakdown.

Input

Send these as a JSON object. Unknown fields are rejected.

input: A whole number such as 2026, or Roman numerals such as MMXXVI. (string, up to 100 characters, required)
vinculum: Allow numbers above 3999 using overlined numerals (×1000). (boolean, default false)

Try it in the browser JSON Schema Get an API key

curl https://pithlab.com/api/v1/tools/roman-numeral-converter \n  -H "Authorization: Bearer $PITHLAB_KEY" \n  -H "Content-Type: application/json" \n  -d '{"input":"2026"}'

Example response

{
  "ok": true,
  "result": {
    "direction": "toRoman",
    "roman": "MMXXVI",
    "vinculum": false,
    "parts": [
      {
        "symbol": "MM",
        "value": 2000
      },
      {
        "symbol": "XX",
        "value": 20
      },
      {
        "symbol": "V",
        "value": 5
      },
      {
        "symbol": "I",
        "value": 1
      }
    ]
  }
}