Roman Numeral Converter

What this tool does

Type a number and instantly see its Roman numeral, or type a Roman numeral and instantly see the number — both fields stay in sync as you type. It also shows exactly how the numeral is built (which symbols add up to which value), flags numerals that aren't written in standard form, and includes a batch mode for converting a whole list at once.

Who it's for

Students working through Roman numeral homework, anyone decoding a copyright year or clock face, people naming a Super Bowl, movie sequel, or monarch, and developers who just need a quick reference while writing a converter of their own.

How to use it

• Type a whole number from 1 to 3999 in the left field and watch the Roman numeral appear on the right, with a breakdown of how it's constructed.
• Or type a Roman numeral directly (like MCMXCIV) and the number fills in automatically.
• If what you typed isn't standard notation (like IIII instead of IV), you'll get a note showing the standard form without your input being rejected outright.
• For a list of values, switch to the batch panel below, pick a direction, paste your list (one per line or comma-separated), and click Convert All.

Real-world uses

Figuring out what year a movie's copyright notice (MCMXCVIII) actually corresponds to. Converting a list of Super Bowl numbers, book/movie sequel numbers, or outline levels in bulk. Double-checking a Roman numeral clock face or a tattoo before it's permanent. Helping with a school assignment on numeral systems.

Frequently asked questions

Why does it stop at 3999?

Standard Roman numerals only have symbols up to M (1000), and the largest value you can build with the usual subtractive rules is 3999 (MMMCMXCIX). Numbers beyond that traditionally use a bar over a numeral to multiply it by 1,000, which isn't practical to type as plain text.

Why is IIII sometimes used instead of IV?

IIII is a historical/decorative variant still seen on some clock faces, but it isn't the standard mathematical notation taught today, which is why the tool flags it while still telling you the correct value.

Can Roman numerals represent zero or negative numbers?

No — the classical Roman numeral system has no symbol for zero and can't represent negative numbers, which is a real limitation of the system, not a bug in this tool.

Does the batch converter handle mixed valid and invalid entries?

Yes, each line is converted independently and any entry that isn't a valid number (1-3999) or valid Roman numeral is clearly marked as invalid rather than breaking the whole batch.

Is MCMXCIV really 1994?

Yes: M (1000) + CM (900) + XC (90) + IV (4) = 1994. Type it into the Roman field above and you'll see that exact breakdown.