Roman Numeral Converter
Convert numbers to Roman numerals and back instantly. Supports 1–3999, batch conversion, year mode, and a subtractive notation reference table.
Reference Table
| Decimal | Roman |
|---|---|
| 1 | I |
| 4 | IV |
| 5 | V |
| 9 | IX |
| 10 | X |
| 40 | XL |
| 50 | L |
| 90 | XC |
| 100 | C |
| 400 | CD |
| 500 | D |
| 900 | CM |
| 1000 | M |
Subtractive Notation Rules
Roman numerals normally add values left to right (e.g. VIII = 8). When a smaller-value numeral appears before a larger one, it is subtracted instead. Only specific pairs are allowed:
- IV = 4 IX = 9(I before V or X)
- XL = 40 XC = 90(X before L or C)
- CD = 400 CM = 900(C before D or M)
No numeral may repeat more than three times consecutively (e.g. III is valid, IIII is not — use IV instead).
How to use Roman Numeral Converter
-
Choose conversion direction
Select 'Number to Roman' to convert a decimal number, or 'Roman to Number' to decode a Roman numeral string.
-
Enter your value
Type a number from 1 to 3999, or type a Roman numeral string. The result appears instantly.
-
Use year mode
Switch to Year mode for quick date and anniversary conversions — commonly used for tattoos, clocks, and event commemorations.
-
Try batch conversion
Paste a list of values in Batch mode to convert multiple numbers or Roman numerals at once.
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Copy the result
Click the copy button to send the converted value to your clipboard.
Roman Numeral Converter FAQ
What are the Roman numeral symbols?
What is subtractive notation in Roman numerals?
What is 2024 in Roman numerals?
What is the range of Roman numerals?
Why are Roman numerals used today?
What is 1999 in Roman numerals?
Is IIII or IV correct for 4?
Can I convert a list of years at once?
How do I read a Roman numeral?
Is any data sent to a server?
Background
Convert any integer between 1 and 3999 to its Roman numeral equivalent, or convert any Roman numeral string back to a decimal value — instantly in both directions. Year mode is optimized for the popular use case of converting birth years, anniversaries, and historical dates to Roman numerals — popular for tattoos, clocks, and commemorative items. Batch mode converts entire lists at once, useful for generating Roman numeral sequences. A built-in reference table explains all seven symbols (I, V, X, L, C, D, M) and the six subtractive pairs with examples. Input validation catches invalid Roman numeral strings and highlights errors. Copy the result in one click. All processing runs in your browser with no server calls or account required.
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