| 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 a standard Roman numeral to an Arabic number and inspect the value of every part. Invalid or nonstandard forms are rejected instead of being guessed.
Subtractive pairs such as IV, IX, XL, XC, CD, and CM are parsed as one value. The converted result is checked against its canonical Roman form to catch invalid ordering or repetition.
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 It is useful for decorative dates, inscriptions, chapter headings, clocks, and historical references.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