Roman Numeral Converter Units
Convert numbers to Roman numerals and back again.
Roman Numeral Converter is a free online tool that convert numbers to Roman numerals and back again. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- Units
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- 1
- Works offline
- Yes, after the first visit
About Roman Numeral Converter
Standard Roman numerals run from 1 to 3,999, because there is no conventional way to write 4,000 without the vinculum — an overbar multiplying a numeral by a thousand — which has no plain-text form. Subtractive notation is used strictly: 4 is IV, 9 is IX, 40 is XL. IIII appears on clock faces for reasons of visual balance, not arithmetic.
How to use it
- Enter number or numeral.
- Results update the moment anything changes.
The one setting
| Setting | What it does | Default |
|---|---|---|
| Number or numeral | Free text. | 2026 |
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
| Controls | Number or numeral |
Questions
Why can it not go above 3999?
Because 4,000 needs M̄ (M with an overbar) or MMMM, and neither is standard plain text. Above 3,999 the system genuinely runs out of conventional notation.
Why do clocks show IIII instead of IV?
Tradition, and symmetry — IIII balances VIII across the dial. One story holds that Louis XIV preferred it. Either way it is a clockmaking convention, not a numbering rule.