Roman numeral converter
Convert both ways and understand every symbol.
1–3999, without signs, separators or leading zeros.
Result
How the number is built
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Read a date on a building, check a chapter number, or write a year in Roman numerals. Enter a whole number from 1 to 3999 to get its Roman spelling, or choose the reverse direction to read letters as a number. The result appears as you type, together with the groups that make up its value. You can see exactly why IV means four and CM means nine hundred. All calculations happen in your browser.
How to use
- Choose numbers to Roman numerals, or the reverse direction.
- Enter one whole number or a Roman numeral using ordinary Latin letters.
- Read the result and follow the addition and subtraction below it.
- Copy the result, or clear the field to remove the saved input.
What it handles
- Checks modern canonical notation, including IV, IX, XL, XC, CD and CM.
- Accepts lowercase letters and trims spaces around the input.
- Rejects zero, fractions, leading zeros and numbers above 3999.
- Keeps the current value and direction in the page query for sharing.
FAQ
Why is IIII rejected when it appears on clocks?
Some clock faces use IIII for four, and historical inscriptions do not always follow modern conventions. This converter deliberately uses canonical subtractive notation, so four is IV and nine is IX. Forms such as IIII, IIV and IC produce an error instead of a guessed answer. If you are transcribing an inscription, keep its original lettering separately from the normalized number.
Can I convert zero or numbers larger than 3999?
The supported range is one through 3999, inclusive. Standard Roman notation in this range has no symbol for zero and does not represent negative numbers or fractions. Larger values can use overbars or other extensions, but those conventions are outside this tool. Enter plain decimal digits without separators, signs or leading zeros; for example, use 2026 rather than 2,026.
How do the breakdown and saved input work?
The explanation splits a numeral into ordinary symbols and valid subtractive pairs. For MCMXCIV, it shows M plus CM plus XC plus IV, or 1000 plus 900 plus 90 plus 4. Your last input is saved locally, and Clear removes it. The page query also contains the value and direction, so anyone receiving that link can see them. Input is limited to 128 characters.
Updated