🏛️Roman Numeral Converter
Two-way conversion — live, validated, with optional breakdown.
Need to read or write Roman numerals? Our free Roman numeral converter translates both ways in an instant. Type a number and see its Roman numeral, or paste a numeral like MCMXCIV and get the number—1994—straight back. Change either side and the other updates live, so you never have to puzzle over the symbols yourself.
It's accurate and forgiving: it follows the standard rules (including subtractive pairs like IV and IX), validates numerals so you'll know if one is written incorrectly, and can show the breakdown so you can see exactly how the value adds up. It covers the standard range from 1 to 3,999. Whether you're decoding a clock face, a movie copyright date, a book chapter, or a monument inscription—or writing numerals for a design or tattoo—you'll get the right answer every time.
Simply enter a number or a numeral to convert instantly. No sign-up, no downloads, no limits—just accurate results whenever you need them.
About the Roman Numeral Converter
Features
Two-way conversion
Type a number to get the Roman numeral, or type a Roman numeral to get the number. Both fields update the other live.
Strict validation
Entered numerals are re-encoded and compared to the canonical form — non-standard forms like IIII, VV, IL, or IC are rejected with a clear message.
Breakdown view
Click "Show breakdown" to see each symbol group and its numeric value — for example, MCMXCIV = M (1000) + CM (900) + XC (90) + IV (4).
Full 1–3,999 range
Covers the entire standard Roman numeral range. Values outside this range (0, negatives, decimals, numbers above 3,999) are caught with a helpful message.
How Roman numerals work
Roman numerals are an additive and subtractive numeral system using seven symbols: I (1), V (5), X (10), L (50), C (100), D (500), and M (1000). Symbols are generally written from largest to smallest, left to right, and their values are added together.
The subtractive rule is the key exception: when a smaller symbol appears immediately before a larger one, its value is subtracted instead of added. There are exactly six valid subtractive pairs in standard notation:
IV = 4
5 − 1
IX = 9
10 − 1
XL = 40
50 − 10
XC = 90
100 − 10
CD = 400
500 − 100
CM = 900
1000 − 100
Any numeral that doesn't follow these rules — such as IIII for 4 or IL for 49 — is non-standard. The converter validates by re-encoding the parsed number and checking that it matches the input exactly.
Frequently Asked Questions
How does the Roman numeral converter work?
Enter a number to see its Roman numeral, or enter a Roman numeral to get the number back. Change either field and the other updates instantly — no button to press.
Is this Roman numeral converter free to use?
Completely free — no sign-up, no downloads, no limits. You can convert as many numbers or numerals as you like.
What range of numbers does it support?
The standard range of 1 to 3,999, which is what classic Roman numerals represent without special extended notation.
Why can't it do 0 or negative numbers?
Roman numerals have no symbol for zero and no standard way to write negatives, so the converter works with positive whole numbers only.
What are subtractive numerals?
Pairs like IV (4) and IX (9) where a smaller symbol placed before a larger one means subtraction. The converter uses and recognises all six standard subtractive pairs: IV, IX, XL, XC, CD, CM.
Will it catch incorrectly written numerals?
Yes. It validates against the standard canonical form — it re-encodes the parsed value and compares it to your input. Non-canonical forms like IIII, VV, IL, or IC are flagged as invalid.
Can it show how a numeral breaks down?
Yes. Click "Show breakdown" to see each symbol group and its value — for example, MCMXCIV breaks into M (1000) + CM (900) + XC (90) + IV (4) = 1,994.
How do I write a year like 2024 in Roman numerals?
Enter 2024 and the converter returns MMXXIV. Any year within 1–3,999 works the same way.
Is my data stored or sent anywhere?
No. Everything runs in your browser — nothing is stored or sent to a server.
Does it work on mobile?
Yes, fully responsive. Both fields and the breakdown display fit any screen without horizontal scrolling.