| Roman part | Value |
|---|
| Roman numeral | Value | Use |
|---|---|---|
| I | 1 | One |
| IV | 4 | One before five |
| V | 5 | Five |
| IX | 9 | One before ten |
| X | 10 | Ten |
| XL | 40 | Ten before fifty |
| L | 50 | Fifty |
| XC | 90 | Ten before one hundred |
| C | 100 | One hundred |
| CD | 400 | One hundred before five hundred |
| D | 500 | Five hundred |
| CM | 900 | One hundred before one thousand |
| M | 1,000 | One thousand |
Convert whole numbers from 1 through 3,999 into standard Roman numerals, or validate and convert Roman numerals back to Arabic numbers.
Automatic detection accepts either input format, and the breakdown shows the value represented by every Roman part.
The symbols I, X, C, and M may repeat where standard notation permits. IV, IX, XL, XC, CD, and CM use subtraction. Noncanonical forms such as IIII, VX, or IC are rejected instead of being silently interpreted.
Date mode converts the day, month, and year separately and supports three display orders. It is useful for decorative dates, inscriptions, chapter headings, clocks, and historical references. Standard notation on this page is limited to years through 3999 because larger values require overline conventions that are not represented consistently in plain text.
Related conversions: Roman Numeral Converter · Roman Numerals to Numbers · Numbers to Roman Numerals · Date Calculator