Roman Numeral Converter

The Roman Numeral Converter converts numbers between one and three thousand into and from Roman numerals, the classic system of I, V, X, L, C, D, and M. It is most useful for display, where you might want to label a section, a chapter, or a clock face in Roman form, and for puzzles that involve the old numeral system. Note that the system has no symbol for zero or for negative numbers, which is why it is a display aid rather than a tool for arithmetic. The tool runs locally in your browser. Roman numerals use a small set of letters, I for one, V for five, X for ten, L for fifty, C for a hundred, D for five hundred, and M for a thousand, combined by addition and by subtraction. The subtractive form is what confuses people: a smaller symbol placed before a larger one is subtracted rather than added, which is why four is written as one before five and nine as one before ten. The system was not designed for arithmetic, having no symbol for zero and no positional notation, which is exactly why it gave way to the decimal system we use for computation. Its remaining role is decorative and structural: chapter numbers, section headings, film and game sequels, clock faces, and formal or traditional contexts where the numeral form carries a certain weight. For that use the converter is simply a convenience, sparing you the need to recall the symbol table and the subtractive rules while producing a label, and it handles the full conventional range up to three thousand nine hundred ninety nine.

📘 Related guide: Convert Roman numerals to numbers and back →