Why is the limit 3999?

Standard Roman numerals only go up to MMMCMXCIX (3999). Numbers 4000 and above require a vinculum (overline bar) notation that's not universally supported. This tool uses the standard 1–3999 range.

What are the subtractive pairs?

Roman numerals use 6 subtractive combinations: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. These avoid repeating a numeral more than 3 times (e.g. 4 is IV not IIII).

Is there a standard for Roman numerals?

Not formally — Roman numerals predate standardization. The subtractive notation (IV, IX, etc.) is the modern convention. Ancient Romans sometimes wrote 4 as IIII (still seen on clock faces) and 9 as VIIII.

Roman Numeral Converter

Runs in browser

Two-way Roman numeral converter (1–3999) with component breakdown.

Convert between Arabic numbers and Roman numerals instantly. Supports 1–3999 in both directions. Shows full breakdown of each numeral component. Validates Roman numeral syntax. Free online tool.

Arabic Number (1–3999)

Result

MMXXIV

Breakdown

M = 1000 × 2

X = 10 × 2

IV = 4

Notable Examples

🔒 Runs in your browser · No uploads · Your data never leaves your device

How to use

Choose direction
Click 'Arabic → Roman' to convert a number to Roman numerals, or 'Roman → Arabic' to convert a Roman numeral to a number.
Enter a value
Type an Arabic number (1–3999) or a Roman numeral (I through MMMCMXCIX). The result appears instantly.
See the breakdown
The breakdown panel shows how each Roman numeral component contributes to the total value.

Common use cases

Converting years to Roman numerals — Convert a year number to Roman numerals for use in film credits, book copyright pages, or formal documents.
Decoding Roman numerals in historic content — Convert Roman numerals found in book chapters, clock faces, or historic documents back to Arabic numbers.

Examples

Convert 2024
Enter 2024 in Arabic → Roman mode
Output
```
MMXXIV · MM=2000, XX=20, IV=4
```
Convert XLII
Enter XLII in Roman → Arabic mode
Output
```
42 · XL=40, II=2
```

Frequently asked questions

Why is the limit 3999?: Standard Roman numerals only go up to MMMCMXCIX (3999). Numbers 4000 and above require a vinculum (overline bar) notation that's not universally supported. This tool uses the standard 1–3999 range.
What are the subtractive pairs?: Roman numerals use 6 subtractive combinations: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. These avoid repeating a numeral more than 3 times (e.g. 4 is IV not IIII).
Is there a standard for Roman numerals?: Not formally — Roman numerals predate standardization. The subtractive notation (IV, IX, etc.) is the modern convention. Ancient Romans sometimes wrote 4 as IIII (still seen on clock faces) and 9 as VIIII.

Key concepts

Roman numeral: A numeral system using letters from the Latin alphabet (I, V, X, L, C, D, M) to represent values — standard range is 1–3999.
Subtractive notation: The convention where IV means 4 (5 − 1) instead of IIII — placing a smaller numeral before a larger one subtracts it.

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