Roman numeral converter
Type 1994 or type MCMXCIV: it is the same field.
A number (1994) or a Roman numeral (MCMXCIV) both work: it tells them apart on its own.
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From 1 to 3999, which is as far as the seven letters go without overbars. Reading a Roman numeral applies the rules to the letter: IIII, IL or XXXX are not translated on the nod — the page says which rule they break and what the correct form is. Typing accepts lower case and stray spaces; the answer always comes back in capitals.
The seven symbols
These seven letters write any Roman numeral. There are no others, and there is nothing above M.
| Symbol | Value | How it behaves |
|---|---|---|
| I | 1 | Repeats up to three times (III). Subtracts from V and X. |
| V | 5 | Never repeats. Never subtracts. |
| X | 10 | Repeats up to three times (XXX). Subtracts from L and C. |
| L | 50 | Never repeats. Never subtracts. |
| C | 100 | Repeats up to three times (CCC). Subtracts from D and M. |
| D | 500 | Never repeats. Never subtracts. |
| M | 1000 | Repeats up to three times (MMM). Subtracts from nothing: there is nothing bigger. |
The ones that repeat are the powers of ten (I, X, C, M) and the ones that do not are the fives (V, L, D): two fives are a ten, and the ten already has a letter. The same logic explains why only I, X and C subtract.
Years around 1994
The highlighted row is yours. Change the number above and this table moves with it.
| Year | In Roman numerals |
|---|---|
| 1989 | MCMLXXXIX |
| 1990 | MCMXC |
| 1991 | MCMXCI |
| 1992 | MCMXCII |
| 1993 | MCMXCIII |
| 1994 | MCMXCIV |
| 1995 | MCMXCV |
| 1996 | MCMXCVI |
| 1997 | MCMXCVII |
| 1998 | MCMXCVIII |
| 1999 | MCMXCIX |
The rules of Roman numerals, including what does not work and why
Roman numerals have seven symbols and about four rules. Once the rules make sense as a system rather than a list to memorise, reading and writing them stops being guesswork.
Two families of symbols
Look at the seven letters and they split cleanly in two. I, X, C and M are the powers of ten: 1, 10, 100, 1000. V, L and D are the fives that sit halfway between them: 5, 50, 500. Almost every rule follows from which family a letter belongs to.
The powers of ten repeat, up to three times: III is 3, XXX is 30, CCC is 300. The fives never repeat, and the reason is arithmetic rather than taste — two fives make a ten, and the ten already has its own letter. VV would be X, LL would be C, DD would be M. Writing them would be spelling a number that already has a shorter spelling.
Why the fourth one subtracts
If the powers of ten repeat three times at most, four of them needs another approach. That approach is subtraction: putting a smaller symbol in front of a larger one means taking it away. IV is 5 − 1 = 4, XL is 50 − 10 = 40, CD is 500 − 100 = 400.
But only the powers of ten subtract, and only from the next two symbols up. That gives exactly six valid subtractions and no more: IV, IX · XL, XC · CD, CM. This is where most mistakes live. IM for 999 is not valid, because I only subtracts from V and X — 999 is CMXCIX. Nor is VX, because V never subtracts at all.
You may still see IIII on clock faces. That is a decorative convention with several competing explanations, none of them arithmetic: on a dial, IIII balances the VIII opposite it visually. It is not the rule, and it is not what anyone writing a date should use.
Reading one: from the left, watching for pairs
To read a numeral, go left to right and add — but whenever a symbol is worth less than the one immediately after it, subtract instead. Take MCMXCIV: M is 1000, then CM is 900 (C before M, so subtract), then XC is 90, then IV is 4. Total 1994. That is precisely the breakdown the converter shows under the answer.
Where the system stops
With ordinary letters you can go up to 3999 = MMMCMXCIX. Past that you would need four Ms, which the repetition rule forbids. Rome's answer was the vinculum: a bar over a symbol multiplying it by a thousand, so V with a bar is 5000. Since those are not characters on a keyboard, this converter stops at 3999.
There is no zero either. The Romans had no symbol for nothing, and wrote the word nulla when they needed one. No negatives, no decimals: fractions were handled separately, in twelfths, with their own names such as uncia and semis.
Why this converter refuses instead of guessing
Type IIII into most converters and they cheerfully return 4. That is a lazy translator, not a calculator. If you are checking whether what you wrote is correct, being told "4" teaches you nothing and leaves the mistake in place. This page tells you which rule is broken and what the correct form is — and where it can, it shows what you probably meant. The value is in the refusal.
Frequently asked questions
What are the seven Roman numeral symbols?
I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1000. There are no others, and there is nothing above M in ordinary use.
Why is 4 written IV and not IIII?
Because I, X, C and M repeat three times in a row at most, and the fourth is solved by subtracting. IIII would be a fourth I in a row, so 4 is written as one less than five: IV. You do still see IIII on clock faces, which is a decorative convention and not the arithmetic rule.
Which subtractions are allowed?
Only six, and only with I, X and C, each in front of the two symbols that follow it: IV and IX, XL and XC, CD and CM. Nothing else. IM for 999 is wrong, because I only subtracts from V and X — 999 is CMXCIX.
Why do V, L and D never repeat?
Because they are the fives, and two fives make a ten, which already has a letter of its own. VV would be X, LL would be C and DD would be M. The same logic explains why they never subtract either.
What is the largest Roman numeral?
With ordinary letters, 3999 = MMMCMXCIX. Above that you need an overbar on the symbol, which multiplies its value by a thousand: V with a bar is 5000. Those are not letters you can type on a keyboard, which is where this converter stops.
How do Romans write zero?
They do not. There was no symbol for nothing, and when it was needed they wrote the word nulla. The system starts at 1, which is I, and has no negatives and no decimals either.
How do you write a year in Roman numerals?
The same way as any other number: 1994 is MCMXCIV and 2026 is MMXXVI. Break it into thousands, hundreds, tens and units and write each part with the largest symbol that fits — that is exactly what the breakdown under the result shows.
Do you store what I type?
No. The conversion happens inside your own browser. What you type never leaves your device: there is no server to receive it and no database to keep it.
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