A Roman numeral converter is a free online tool that translates between ordinary numbers and Roman numerals in both directions. Enter any number from 1 to 3999 to get its numeral instantly, or paste a numeral like MCMXCIV to get the number back with strict validation, all with no signup.
Number to Roman
Roman to Number
Roman numeral chart
How do Roman numerals work?
Roman numerals use seven letters: I (1), V (5), X (10), L (50), C (100), D (500) and M (1000). Symbols are normally written largest to smallest and added together, but a smaller symbol before a larger one means subtraction, which is how IV means 4 and CM means 900.
Only six subtractive pairs are standard: IV, IX, XL, XC, CD and CM. You will see this system on clock faces, book chapters, movie sequels, monarch names and cornerstones, and it is still taught as the canonical form in schools.
How do you convert a number to Roman numerals?
Break the number into thousands, hundreds, tens and ones, then write each part with the largest symbols first. For 2026: 2000 becomes MM, 20 becomes XX, and 6 becomes VI, giving MMXXVI. Subtractive pairs handle the 4s and 9s, keeping the result compact and standard.
The converter above does this instantly and guards the 1-3999 range, since classical notation has no symbol above M and no representation for zero.
Why is 4 written as IV instead of IIII?
Subtractive notation (IV for 4, IX for 9) became the standard because it is shorter and clearer than repeating a symbol four times. Repeating IIII does appear on some traditional clock faces, but IV is the form schools, style guides and this converter use.
The same logic applies at every scale: XL for 40, XC for 90, CD for 400 and CM for 900. A smaller value may only precede the next two larger values, which is why IL for 49 is invalid and must be XLIX.
How do you read a Roman numeral like MCMXCIV?
Scan left to right, adding values but subtracting when a smaller symbol precedes a larger one. MCMXCIV breaks into M (1000) + CM (900) + XC (90) + IV (4) = 1994. Paste any numeral into the converter above to have it parsed and validated automatically.
If the numeral breaks the rules, for example VX or XM, the tool flags it and names the valid subtractive pairs so you can fix it.
FAQs
Is this Roman numeral converter free?
Yes. Convert as many numbers and numerals as you like with no account, no watermark and no limits.
Why does it only accept 1 to 3999?
Standard Roman numerals have no symbol above M (1000), so numbers beyond 3999 need non-standard extensions like overlines. The tool validates the classical 1-3999 range.
Why is 4 written as IV and not IIII?
Subtractive notation places a smaller symbol before a larger one to mean subtraction: IV is 5 minus 1. This is the standard taught in schools and used on clocks and monuments.
How does the validator catch bad numerals?
It checks the full numeral against the classical grammar: symbols in descending order with only the six allowed subtractive pairs (IV, IX, XL, XC, CD, CM). Anything else, like VX or IL, is rejected with an explanation.
Is zero a Roman numeral?
No. The Romans had no symbol for zero, so the converter starts at 1 (I). Entering 0 or a negative number shows a range error.