Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals back to numbers, from 1 all the way to 3,999,999. Free and instant — everything runs privately in your browser.
| Symbol | Value |
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How to use the Roman numeral converter
- Choose a direction. Pick "Number → Roman" to translate a regular number, or "Roman → Number" to decode a numeral like MMXXVI.
- Type your value. Numbers from 1 to 3,999,999 are supported. For Roman input you can type upper or lower case letters, paste numerals with overlines, or use the plain-text form like (XII)CDLVII.
- Read the result and breakdown. The conversion appears instantly with a symbol-by-symbol table showing how the numeral adds up. Use the copy buttons to grab either form.
About this tool
This free Roman numeral converter translates in both directions and validates that numerals follow the standard subtractive rules — so IV is accepted but IIII is flagged. Classic Roman numerals only reach 3,999 (MMMCMXCIX), so for larger values the tool uses vinculum notation: a bar drawn over a letter multiplies it by 1,000, letting a single numeral express anything up to 3,999,999. That makes it handy for movie copyright dates, clock faces, book chapters, monument inscriptions, tattoo designs and history homework alike.
The converter runs entirely in your browser with no server round-trips — nothing you type is uploaded or stored. Results come with a breakdown table that shows the value of every symbol, which is a great way to learn how additive and subtractive pairs like XC (90) and CM (900) actually work.
Frequently asked questions
Why does the converter stop at 3,999,999?
Standard numerals top out at 3,999 because a symbol may repeat at most three times. Vinculum notation multiplies an overlined group by 1,000, and since that group is itself limited to 3,999, the largest expressible number is 3,999 × 1,000 + 999 = 3,999,999.
How do I type a Roman numeral with an overline?
The easiest way is to paste one this tool copied for you — it uses the Unicode combining overline character. Alternatively, wrap the overlined part in parentheses: (XII)CDLVII means 12,457, because the XII inside the parentheses is multiplied by 1,000.
Why is IIII rejected when some clocks use it?
The tool enforces standard (subtractive) form, where 4 is written IV and each symbol appears at most three times in a row. The IIII seen on many clock faces is a traditional decorative variant, not standard notation, so it is flagged as invalid here.
Is there a Roman numeral for zero or negative numbers?
No. The Roman system has no symbol for zero and no concept of negative numbers — it was built for counting and recording quantities. That is why this converter accepts whole numbers starting at 1.