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An online tool for bidirectional conversion between Arabic numerals and Roman numerals within the range of 1 to 9999. It automatically detects the input type and supports one-click copying of conversion results.
| Arabic Numeral | Roman Numeral | Description |
|---|---|---|
| 1 | I | Basic unit symbol |
| 5 | V | Basic unit symbol |
| 10 | X | Basic unit symbol |
| 50 | L | Basic unit symbol |
| 100 | C | Basic unit symbol |
| 500 | D | Basic unit symbol |
| 1000 | M | Basic unit symbol |
Roman numerals are a numeral system originating from ancient Rome, widely adopted before the popularization of Arabic numerals. Though less commonly used in daily life nowadays, they still appear frequently on clock dials, serial numbering, calendar labels, building plaques, periodic table indices and more. Roman numerals consist of only seven basic characters with the following value mappings: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. All Roman numerals are formed by combining these seven characters following addition and subtraction rules. Below is a reference of common Roman numerals, calculation rules and their Arabic numeral equivalents:
| Arabic Numeral | Roman Numeral | Calculation Rule |
|---|---|---|
| 1 | I | Basic symbol |
| 2 | II | 1+1 |
| 3 | III | 1+1+1 |
| 4 | IV | 5−1 (subtraction rule) |
| 5 | V | Basic symbol |
| 6 | VI | 5+1 |
| 7 | VII | 5+1+1 |
| 8 | VIII | 5+1+1+1 |
| 9 | IX | 10−1 (subtraction rule) |
| 10 | X | Basic symbol |
| 14 | XIV | 10+(5−1) |
| 19 | XIX | 20−1 |
| 40 | XL | 50−10 |
| 58 | LVIII | 50+5+1+1+1 |
| 90 | XC | 100−10 |
| 144 | CXLIV | 100+(50−10)+(5−1) |
| 400 | CD | 500−100 |
| 900 | CM | 1000−100 |
| 1994 | MCMXCIV | 1000+900+90+4 classic example |
| 4000 | MMMM | 4×1000 extended thousands notation |
| 5000 | MMMMM | 5×1000 extended thousands notation |
| 9000 | MMMMMMMMM | 9×1000 extended thousands notation |
| 9999 | MMMMMMMMMCMXCIX | 9000+900+90+9 maximum supported value |
more.