Roman Numeral Converter – Roman to Number & Number to Roman

Roman Numerals originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Today, they are still widely used in clock faces, book chapters, and copyright dates.

This professional converter provides instant, bidirectional translation between modern Hindu-Arabic integers (1, 2, 3…) and standard Roman notation (I, II, III…). It includes strict validation to ensure historical accuracy for standard inputs.

Decimal Number

Arabic

DEC

Standard integer format (Range: 1 – 3,999).

Roman Numeral

Latin

ROM

Valid characters: I, V, X, L, C, D, M.

Technical Context & Limits

Roman numerals use seven symbols: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). The system is generally additive, but uses subtractive notation (like IV for 4) to ensure brevity.

Why is the maximum limit 3,999?

The largest standard Roman symbol is M (1,000). Standard notation follows the “Rule of Three,” which forbids repeating a symbol more than three times consecutively. Therefore, 4,000 cannot be written as MMMM.

Historically, Romans indicated numbers 4,000 and higher by placing a Vinculum (a horizontal bar) over the numeral to multiply it by 1,000 (e.g., IV = 4,000). Since standard computer keyboards and ASCII text do not support these overline characters, digital converters typically cap at MMMCMXCIX (3,999).

References

How to Use This Converter

Convert numbers instantly between standard digits and Roman format.

Enter a Number

Type a year (e.g., 2025) in the Decimal field or letters (e.g., MMXXV) in the Roman field.

Automatic Validation

The tool automatically checks for invalid formats or characters (e.g., IIII is invalid) and updates instantly.

Copy Result

Use the button to copy the converted value for use in your documents.