Developer tool
Roman Numerals Converter
Convert numbers to Roman numerals and Roman numerals back to numbers instantly in your browser.
Processed entirely in your browser. No value is uploaded.
Use the toolNo account required
Use a whole number between 1 and 3999.
Enter a value to see the converted result.
Common values
1I
4IV
9IX
40XL
90XC
400CD
900CM
2026MMXXVI
3999MMMCMXCIX
Core symbols
1I
5V
10X
50L
100C
500D
1000M
Common subtractive pairs: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900.
How it works
Canonical Roman numerals, both ways.
Convert standard integers from 1 to 3999 or validate a Roman numeral by converting it back to its canonical form. Subtractive pairs such as IV, IX, XL, XC, CD, and CM are supported.
Standard range
Values outside 1–3999 and non-canonical spellings are rejected instead of being silently reinterpreted.