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Roman Numeral Converter
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// about this tool

Roman Numeral Converter Online

Updated 2026-08-19

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

// examples

Number to Roman numerals
Input
2024
Output
MMXXIV
Roman numerals to number
Input
XLII
Output
42
Subtractive notation
Input
94
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

Is my input uploaded to a server?
No. The conversion runs entirely in your browser, so nothing is uploaded and your data never leaves your machine.
What range of numbers is supported?
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.
Does it convert both directions?
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.
Why does it say my Roman numeral is invalid?
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.
What is the difference between this and the Number Base Converter?
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.

// works with your data

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Use this via API

Get a free API key → 
curl -X POST https://thesnaptools.com/api/v1/tools/roman-numerals \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"value":"2024"}'