Free Roman Numeral Converter
The Roman Numeral Converter turns numbers (1–3999) into Roman numerals and Roman numerals back into numbers. Type in either field and the other updates instantly.
If you need other numbering systems, the Number Base Converter covers binary through hexadecimal.
How to use the Roman Numerals
- 1 Type a number to convert it to Roman numerals, or type numerals to convert them back to a number.
- 2 The tool detects which direction you mean as you type.
- 3 Read the result, along with the breakdown of each symbol if you want to see how it was built.
- 4 Use the reference list of symbols to check unfamiliar ones.
How to Use
Enter a number to get its Roman numeral, or type a Roman numeral to get the number. Standard subtractive notation is used (IV, IX, XL, XC, CD, CM).
- Numbers 1 to 3999
- Standard subtractive notation
- Two-way live conversion
Frequently asked questions
What is the largest number Roman numerals can write?
3,999, as MMMCMXCIX, using standard notation. The system has no zero and no symbol above M, so larger values need a bar over a letter to mean "multiply by 1,000" — an extension, not part of the classic system.
Why is 4 written as IV instead of IIII?
Subtractive notation — a smaller symbol before a larger one subtracts, so IV is 5 minus 1. It was not universal in antiquity; clock faces often use IIII for 4 for visual balance opposite VIII, and that is still the convention on many watches today.
Are Roman numerals case sensitive?
Not strictly — lowercase (mcmxciv) is understood. Uppercase is the standard for formal use, and it is what you see on buildings, copyright dates and film credits. The converter accepts either.
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