Roman Numeral Converter

1984 ⇄ MCMLXXXIV.

About Roman Numeral Converter

A Roman numeral converter turns a whole number from 1 to 3999 into Roman numerals, and reads a numeral such as MCMLXXXIV back into a number.

How to use

  1. Type a number or a Roman numeral. In Auto mode, digits convert to Roman and letters convert to a number; the switch at the top forces either direction.
  2. The result appears as you type and has a Copy button.
  3. Invalid input shows an error below the panel instead of a result.

What it supports

  • Numbers from 1 to 3999 inclusive. There is no Roman zero, and 4000 and above would need the overline (vinculum) notation, which is not supported.
  • Standard subtractive form: IV not IIII, XC not LXXXX, with at most three repeats of I, X, C and M.
  • Lowercase input is accepted and read as uppercase.
  • Non-standard forms such as IIII, VX or IC are rejected as invalid rather than guessed at.
  • Input is limited to 16 characters.

Example

1984      → MCMLXXXIV
MMXXVI    → 2026
3999      → MMMCMXCIX

Privacy

Runs in the browser. No request is made, and nothing is stored.

Frequently asked questions

What are the Roman numeral symbols and their values?
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000. Symbols are added left to right, except that a smaller symbol before a larger one is subtracted: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900.
Why do Roman numerals only go up to 3999?
Because M (1000) is the largest symbol and standard rules allow at most three repeats, MMMCMXCIX = 3999 is the largest number writable without extra notation. Larger numbers used a bar over a numeral to multiply it by 1000.
Is IIII a valid Roman numeral for 4?
Not in the standard subtractive system, which writes IV. IIII does appear on many clock faces, mostly for visual balance against VIII, and was common in ancient inscriptions.
How do I write 2026 in Roman numerals?
MMXXVI: MM = 2000, XX = 20, VI = 6. Film credits and building cornerstones still use this form for years.