Roman Numeral Converter Online Free (Both Ways)

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Roman Numeral Converter — arabic ↔ roman in your browser

Direction

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Result will appear here

Roman Numeral Converter Online

Updated 2026-07-09

Convert between Arabic numbers and Roman numerals (1–3999) in both directions, right in your browser. Type a number to get its Roman form, or type Roman numerals to convert them back, and SnapTools shows the result instantly with one-click copy or download. Nothing is uploaded: the conversion runs locally, so your data never leaves your machine.

Translating Roman numerals by hand is fiddly once subtractive notation like IX or XL is involved. Whether you're reading a date carved on a building, numbering an outline, or checking your own work, the Roman Numeral Converter gives you an accurate answer in one step.

// how to use

1 Type an Arabic number (1–3999) into the input panel to get Roman numerals on the right.
2 Or type Roman numerals into the input to convert them back to an Arabic number — it works both directions.
3 Read the converted result on the right, then click Copy or Download.

// examples

Number to Roman numerals

Input

Output

MMXXIV

Roman numerals to number

Input

XLII

Output

Subtractive notation

Input

Output

XCIV

// common uses

Reading dates on clocks, books, and buildings Numbering chapters, outlines, or appendices Decoding copyright and movie release years Checking a Roman numeral you wrote by hand

// faq

No. The conversion runs entirely in your browser, so nothing is uploaded and your data never leaves your machine.

Standard Roman numerals cover 1 to 3999. There is no symbol for zero and no standard notation above 3999, so values outside that range are flagged.

Yes. Enter an Arabic number to get Roman numerals, or enter Roman numerals to get the number back — the converter detects which way you're going.

The numeral must follow standard rules — for example, IIII is not valid (IV is), and a symbol can only repeat up to three times. Invalid sequences are rejected.

This translates between Arabic numbers and Roman numerals, while the Number Base Converter switches between bases like decimal, hex, and binary. Use whichever notation you need.

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Use this via API

Get a free API key →

curl -X POST https://snaptools.dev/api/v1/tools/roman-numerals \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"value":"2024"}'