Roman Numeral Converter
Convert a number (1–3999) to a Roman numeral, or a Roman numeral back to a number. Malformed numerals are rejected. Calculated in your browser.
- Runs entirely in your browser
- No sign-up, no watermark
- Free and unlimited
🔒 Your file stays on your device
How to use Roman Numeral Converter
- 1
Open Roman Numeral Converter and fill in the fields.
- 2
Pick any options that apply.
- 3
Read the result straight away — it recalculates as you type.
What you get
- Both directions
- Range 1–3999
- Rejects malformed numerals like IIII
What happens to your files
This tool runs entirely in your browser. The file you choose is read into memory, processed on your device, and offered back as a download. Nothing is uploaded and nothing is kept once you leave the page.
There is no account, no email, no watermark and no daily limit. Come back whenever you need it.
Frequently asked questions
- Why only up to 3999?
- Standard Roman numerals have no symbol above M (1000), so 3999 (MMMCMXCIX) is the largest that can be written without overlines or other extensions.