Roman Numeral Converter

About this roman numeral converter

Convert between whole numbers and Roman numerals in either direction, right in your browser. Choose a direction, enter a whole number from 1 to 3,999 to get its Roman numeral, or enter a Roman numeral using the letters M, D, C, L, X, V, and I to get its numeric value; numeral input is checked against the canonical subtractive-notation form, so malformed numerals like "IIII" are rejected. Use this workspace to prepare a result you can review before putting it to use. All processing takes place on your device, without an account or an upload of your inputs. Check the examples to understand the expected output, read the limitations for the supported scope, and reset the form when you want to start a separate task.

How it works

Builds the Roman numeral greedily from the largest matching value-symbol pair (M, CM, D, CD, C, XC, L, XL, X, IX, V, IV, I); the reverse direction sums symbol values, subtracting a symbol that precedes a larger one, and rejects any input that doesn't re-encode to the same numeral.

Try these examples

MCMXCIV

1994

Limitations & privacy

Supports the standard range of 1 to 3,999; Roman numerals have no symbol for zero or negative numbers. Only canonical subtractive-notation numerals are accepted as valid input.

Inputs and results stay in this browser. Only tool identifiers are stored for your recently used tools. You can clear that history from the directory.

A few good questions