Roman Numeral Converter — Numbers to Roman and Back

Convert numbers to Roman numerals and back, with strict validation of the numeral you type. Free, no sign-up, and your files never leave your device.

Free, with no sign-up and no watermark. The file is processed in your browser and never uploaded.

Convert numbers from 1 to 3999 into Roman numerals and back again. The converter checks the numeral you type and suggests the correct form when it isn’t standard (for example IIII → IV).

Step by step

  1. Type a number: Enter it in Number (1–3999) to see the numeral.
  2. Or type a numeral: Enter letters in Roman numeral to get the number.
  3. Fix mistakes: If a numeral isn’t valid, the message suggests the correct one.
  4. Copy: Use Copy on the result.

Handy for

Dates on buildings and films

Read years like MCMXCIV (1994).

Outlines

Number sections with Roman numerals.

Tattoos and engravings

Get a date right before it’s permanent.

Study

Practise the subtractive rules.

Good to know

  • Only I, X, C and M can repeat, up to three times.

Questions

Why stop at 3999?

Standard numerals have no symbol above M. Larger numbers were written with a bar over letters (vinculum), but there is no single agreed modern notation.

Is anything sent to a server?

No. Every calculation runs in your browser, so the numbers you type never leave your device. The page keeps working offline once it has loaded.

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