Roman Numerals
Numbers to Roman numerals.
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About Roman Numerals
Convert numbers to Roman numerals and Roman numerals back to numbers, both at once. Type any whole number from 1 to 3999 to see its Roman numeral, or type a Roman numeral to read its value. It converts live in both directions and flags out-of-range numbers and malformed numerals right away.
The tool is completely free with no sign-up, no limits, and no ads to click through. Everything runs entirely in your browser using plain JavaScript, so your input never leaves your device and there is nothing to install.
Frequently asked questions
- Is the Roman numeral converter free to use?
- Yes, it is completely free with no account, sign-up, or usage limits. You can convert as many numbers and numerals as you like.
- Is my data uploaded to a server?
- No. All conversion happens locally in your browser with JavaScript. Nothing you type is sent, stored, or logged anywhere, so it works even offline once the page has loaded.
- What range of numbers can it convert?
- Standard Roman numerals cover 1 to 3999. There is no zero and no simple symbol for 4000 or above, so numbers outside 1–3999 are rejected with a clear message.
- Why is a numeral like IIII or IC marked invalid?
- The tool only accepts the standard subtractive form used today. Four is written IV (not IIII) and ninety-nine is XCIX (not IC), so non-standard spellings are flagged as invalid.
- Can it convert Roman numerals back to numbers?
- Yes. It is a two-way converter: enter a number to get its numeral, or enter a numeral (like MMXXVI) to get the number. Both fields update instantly and independently.
- Does capitalization or spacing matter when I enter a numeral?
- No. Lowercase letters are treated the same as uppercase and spaces are ignored, so 'mmxxvi' and 'MM XX VI' both read as 2026.