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Roman Numeral Converter
Convert any number from 1 to 3999 into Roman numerals, or turn a Roman numeral back into a number, with this free Roman numeral converter. It follows the standard rules strictly — so 49 comes out as XLIX, not XXXXVIIII — and if you type a numeral the wrong way, like IIII, it tells you why and shows the correct form. Handy for board classes, book chapters, film years, tattoos and homework.
Whole numbers only, from 1 up to 3999 — the largest value standard Roman numerals can write is MMMCMXCIX (3999).
How to use
- Pick the direction: Number → Roman numerals or Roman numerals → Number.
- Type your value — a whole number from 1 to 3999, or a Roman numeral such as XLIX.
- Press Convert (the answer also updates as you type).
- Read the result with its breakdown. If a numeral breaks a rule, the tool explains the mistake instead of guessing.
Roman numerals at a glance
| Number | Roman | Number | Roman | Number | Roman |
|---|---|---|---|---|---|
| 1 | I | 10 | X | 100 | C |
| 2 | II | 14 | XIV | 200 | CC |
| 3 | III | 19 | XIX | 400 | CD |
| 4 | IV | 20 | XX | 500 | D |
| 5 | V | 40 | XL | 900 | CM |
| 6 | VI | 49 | XLIX | 1000 | M |
| 7 | VII | 50 | L | 1999 | MCMXCIX |
| 8 | VIII | 90 | XC | 2026 | MMXXVI |
| 9 | IX | 99 | XCIX | 3999 | MMMCMXCIX |
How it works
Roman numerals are built from seven letters: I (1), V (5), X (10), L (50), C (100), D (500) and M (1000). To write a number, you break it into thousands, hundreds, tens and ones, and write each part with the letters for that place. 2026 is 2000 + 20 + 6, which becomes MM + XX + VI = MMXXVI. When the digits are added in descending order like this, you simply add the letter values together to read the number back.
The subtractive rule is what keeps numerals short. Without it, 9 would be VIIII and 49 would be XXXXVIIII. Instead, whenever a digit is 4 or 9 in any place, you write the letter for one-less-than the next value: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). Only I, X and C can be used subtractively, and each can subtract only from the next two values above it — I from V and X, X from L and C, C from D and M. That is why 49 is XLIX (40 + 9) and never IL, and why 99 is XCIX and never IC.
Three more rules keep the system tidy. First, I, X, C and M can repeat at most three times in a row — III is 3, but 4 must be IV. Second, V, L and D never repeat, because VV would just be X. Third, letters are written from largest to smallest, apart from the subtractive pairs. This converter checks all of these rules. If you type IIII, it will not silently accept it: it explains that I can repeat only three times and that 4 is written IV. If you type a value whose letters are legal but the arrangement is not, it shows the correct arrangement for the same total.
The limits of the system are real. There is no Roman zero — the Romans simply wrote nothing, or the word "nulla" — so this converter starts at 1. And without extra symbols, the biggest standard number is 3999 (MMMCMXCIX): M can repeat only three times. Medieval writers drew a line over a numeral (a vinculum) to multiply it by 1000 and reach bigger values, but that is not part of the standard system taught in schools. In India you meet Roman numerals daily in school itself: board classes are Class X and Class XII, books and exam papers number chapters and sections with them, film credits print the production year (a 1999 film is MCMXCIX), and clocks, watches and building foundation stones still use them for style.
Worked example
A student wants the year 2026 in Roman numerals for the title page of a school project. Her textbook also numbers an exercise XLIX, and she wants to know what number that is. First, the year.
Step 1: Split 2026 into places: 2000 + 20 + 6.
Step 2: Thousands: 2000 = MM. Tens: 20 = XX. Ones: 6 = VI.
Step 3: Join them in order: MM + XX + VI = MMXXVI.
Step 4: Check the tricky one: 49 = 40 + 9 = XL + IX = XLIX.
The converter above opens with 2026 already converted to MMXXVI, with the breakdown MM = 2000, XX = 20, VI = 6 shown under the result. Switch the direction and type XLIX, and it gives you 49 back — the same two answers, worked both ways.
FAQ
What is 49 in Roman numerals?
49 in Roman numerals is XLIX. It is built as 40 plus 9: XL is 50 minus 10, and IX is 10 minus 1. It is never written as IL, because I can subtract only from V and X — for the tens place, the subtraction must use X before L.
Why is IIII wrong for 4?
Because the letters I, X, C and M may repeat at most three times in a row. Four in a row breaks the rule, so 4 is written with the subtractive form IV — one before five. The only famous exception is on clock faces, where many clockmakers traditionally use IIII for style and symmetry, but in standard writing IV is correct.
What is the largest number in Roman numerals?
The largest standard Roman numeral is 3999, written MMMCMXCIX. M can repeat at most three times, which caps the thousands at 3000, and the hundreds, tens and ones cap at 900, 90 and 9. Bigger values need a vinculum — a line over the numeral multiplying it by 1000 — which is outside the standard system.
Did the Romans have a zero?
No. Roman numerals have no symbol for zero, because the system was built for counting and recording quantities, not for place-value arithmetic. When a Roman writer needed to say "nothing", they used the Latin word nulla. This is also why the converter on this page starts at 1.
How do I read a year like MCMXCIX on a film?
Read it in chunks from the left: M is 1000, CM is 900 (1000 minus 100), XC is 90 (100 minus 10), and IX is 9 (10 minus 1). Add them: 1000 + 900 + 90 + 9 = 1999. Film and TV credits print the production year this way, a habit left over from early cinema.
Why are school classes written as Class X and Class XII?
Indian boards follow the common convention of numbering classes with Roman numerals, so Class 10 is Class X and Class 12 is Class XII. X is 10, and XII is 10 + 1 + 1 = 12. The same style is used for book chapters, volume numbers and the names of kings, queens and popes.