Convert Roman numerals (I, V, X, L, C, D, M) to and from ordinary Arabic numbers. Type a number to get the Roman numeral, or type a Roman numeral to get the number — the direction is detected automatically and both are shown. Handy for clock faces, chapter and volume numbers, movie sequels, copyright years, and watch dials when you need to know "which number is this?". It follows the standard additive/subtractive notation (1–3999) and flags invalid sequences such as IIII or VX. Everything is computed locally; your input is never stored or uploaded (only your upper/lower-case preference is saved on this device).
How to use
- Type a number (e.g. 2024) or a Roman numeral (e.g. MMXXIV) in the box.
- The direction is detected automatically — both the Arabic number and the Roman numeral are shown.
- Toggle upper / lower case if needed, then copy the result.
FAQ
What range is supported?
Standard Roman numerals cover 1–3999. Zero, negative numbers, values of 4000 and above, and decimals are not supported (there is no standard Roman notation for them).
How are Roman numerals written?
The symbols are I=1, V=5, X=10, L=50, C=100, D=500, M=1000, placed largest-first and added together. Putting a smaller symbol before a larger one subtracts it, as in IV=4 or IX=9 (subtractive notation). This tool follows that standard form.
Is my input stored?
No. Conversion runs entirely in your browser; your input is never stored or uploaded. Only your upper/lower-case preference is saved on this device.
Why won't IIII or VX convert?
They are invalid in standard Roman numerals. 4 is written IV and 95 is XCV (IIII and VX break the rules). Only valid sequences are converted to a number.