Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals back to numbers (1–3999). Free and private, right in your browser.
Number to Roman numeral
Roman numeral to number
Convert whole numbers to Roman numerals or decode a Roman numeral back into a regular number, handy for reading movie copyright years, clock faces, Super Bowl numbers, or book chapter headings, and for getting a tattoo or engraving exactly right before it's permanent.
How to use it
- Type a number (1–3999) or a Roman numeral into the box
- The tool detects the direction and converts instantly as you type
- Copy the result to use in your date, title, or design
Frequently asked questions
- What's the largest number this can convert?
- Standard Roman numerals top out at 3,999 (MMMCMXCIX) since there's no symbol for 5,000 or beyond without special notation. Enter 4000 or higher and the converter will flag it rather than guess.
- Does it handle non-standard forms like IIII instead of IV?
- The converter reads back subtractive notation (IV, IX, XL, CM, etc.) correctly since that's the standard modern form, but it won't validate archaic or additive variants like IIII for 4. Stick to standard notation for reliable results.
- Why would I need this instead of just memorizing the rules?
- The subtractive rules (when to write IV vs IIII, or CM vs DCCCC) trip people up constantly on clock faces, movie copyright years, book chapter numbers, and tattoo designs. This just does the lookup instantly in both directions.
- 1
Nothing is uploaded
The file never leaves your device. There is no server to send it to, so there is nothing to leak, log, or subpoena.
- 2
No signup, no limits
No account, no email, no daily cap, no watermark, and no paid tier waiting behind the third file.
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Works offline
Load the page once and it keeps working with the network off, because all the work was always happening locally.