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Roman Numeral Converter

numberClient-side utility

Roman numerals still appear in copyright dates, chapter headings, clock faces, and formal outlines — and converting them by hand invites errors. The Roman Numeral Converter works both directions: type a number (1–3999) and get its Roman form, or type a Roman numeral like MMXXIV and get the Arabic value. Conversion follows standard subtractive notation (IV for 4, IX for 9, XL for 40, CM for 900). Out-of-range numbers get a clear "Enter 1–3999" message, since traditional Roman numerals do not extend beyond that. Everything runs locally in your browser using client-side JavaScript. The tool does not intentionally send your input to our servers.

✓ In-Browser Execution✓ Free & No Usage Cap✓ Zero Server Data Storage

📖How to Use This Tool

What is Roman Numeral Converter?

This converter translates between Arabic numbers and Roman numerals in both directions. Number-to-Roman uses the classic greedy algorithm over the value table (M=1000, CM=900, D=500, CD=400, C=100, XC=90, L=50, XL=40, X=10, IX=9, V=5, IV=4, I=1). Roman-to-number scans left to right, subtracting a symbol's value when a smaller value precedes a larger one.

The supported range is 1 to 3999 — the conventional limit of standard Roman notation. Entering anything outside it shows "Enter 1–3999" instead of a wrong answer.

How to use it

To convert a number: type it into the Number (1-3999) field and click → Roman. The result shows as N = ROMAN (e.g. 2024 = MMXXIV).
To convert a numeral: type it into the Roman (e.g. MMXXIV) field and click → Number. The result shows as ROMAN = N.

Why use this over alternatives

Mental conversion is error-prone past the basics, and many converter pages bury the answer in ads. This tool converts both directions with one click each and validates the range. It runs locally in your browser using client-side JavaScript. The tool does not intentionally send your input to our servers.

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❓Frequently Asked Questions

Q.Why is the range limited to 1–3999?

Standard Roman numeral notation has no widely agreed symbols beyond 3999 (MMMCMXCIX), so the tool enforces this limit. Entering 0, a negative number, or anything above 3999 shows "Enter 1–3999" instead of producing a non-standard result that other readers would not recognize.

Q.Does it accept lowercase Roman numerals?

Yes. Input is uppercased before parsing, so "mmxxiv" converts just like "MMXXIV", and mixed case like "MmXxIv" works too. The output always displays the canonical uppercase form, e.g. `MMXXIV = 2024`, regardless of how you typed the input.

Q.How does it handle subtractive pairs like IV or CM?

Correctly. The parser subtracts a symbol's value when it precedes a larger one, so IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, and CM = 900. Non-standard forms like IIII are still parsed by simple addition, giving 4 as well.

Q.Is my input sent to a server?

No. Conversion runs locally in your browser using client-side JavaScript, applying the greedy value-table algorithm on your device. Nothing is transmitted during the process. The tool does not intentionally send your input to our servers.

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