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Roman Numeral Converter

Convert numbers to Roman numerals & back.

100% private — runs in your browser, nothing is uploaded.

Supports 1–3,999,999. Values above 3,999 use an overline (e.g. V̅ = 5,000) to mean ×1,000, following the classical vinculum notation.

How to use the Roman Numeral Converter

  1. 1
    Choose a direction

    Decide whether you have a number or a Roman numeral to convert.

  2. 2
    Type it in

    Enter your value in the matching field.

  3. 3
    Read the result

    The other field updates instantly with the conversion.

  4. 4
    Copy it

    Use the copy button to grab the result.

Examples

InputOutput
2026MMXXVI
MCMLXXXIV1984
4 / 9 / 40IV / IX / XL

Free online Roman numeral converter

This Roman numeral converter works both ways: type a number to get its Roman numeral, or type a Roman numeral to get the number. It is perfect for tattoos, anniversaries, clock faces, movie copyright years, book chapters and homework.

How Roman numerals work

Roman numerals combine seven letters — I, V, X, L, C, D and M — to build values. You add symbols from largest to smallest (e.g. MDCLXVI = 1666), and use subtractive notation for 4s and 9s: IV = 4, IX = 9, XL = 40, CM = 900.

Beyond 3,999

Classic numerals only reach 3,999 (MMMCMXCIX). For larger numbers, an overline (called a vinculum) multiplies a symbol by 1,000 — so V̅ is 5,000 and X̅ is 10,000. This tool handles values up to 3,999,999 and validates every numeral, so you always get a correct, standard result. It runs in your browser, so it is instant and private.

Frequently Asked Questions

How do I convert a number to Roman numerals?

Type a number in the Number field and the Roman numeral appears instantly. For example, 2026 becomes MMXXVI. You can also type a Roman numeral to convert it back to a number.

What are the basic Roman numeral symbols?

I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000. Other values are built by combining these, using subtraction for 4s and 9s (IV = 4, IX = 9).

How does subtractive notation work?

A smaller symbol before a larger one is subtracted: IV is 4 (5−1), IX is 9, XL is 40, XC is 90, CD is 400 and CM is 900. This keeps numerals short and is why 'IIII' is not standard.

What is the largest number I can convert?

This tool supports 1 to 3,999,999. Standard Roman numerals stop at 3,999 (MMMCMXCIX); above that, an overline (vinculum) multiplies a symbol by 1,000, so V̅ means 5,000.

Why is my Roman numeral rejected?

The tool validates the numeral by converting it back and comparing. Malformed inputs like 'IIII', 'VV' or 'IC' are rejected because they are not valid standard Roman numerals.

Is it private and free?

Yes. Conversions happen entirely in your browser, so nothing is uploaded and it works offline, with no sign-up.

From the blogHow Roman Numerals WorkThe seven Roman numeral symbols, subtractive notation, how to read and write any year, why IIII appears on clocks, and why the system has no zero.Read the full guide

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