Roman Numeral Converter
Type a number from 1 to 3999 to get its Roman numeral, or type a Roman numeral such as MCMXCIV to get the number. The tool detects which you entered, rejects malformed numerals, and lists the symbols and the current year for reference. Free, no sign-up.
Direction
Roman Numeral Reference
| Number | Roman numeral |
|---|---|
| 1 | I |
| 4 | IV |
| 5 | V |
| 9 | IX |
| 10 | X |
| 40 | XL |
| 50 | L |
| 90 | XC |
| 100 | C |
| 400 | CD |
| 500 | D |
| 900 | CM |
| 1000 | M |
| 2026 (this year) | MMXXVI |
How to Use the Roman Numeral Converter
- 1. Type your input. Enter a whole number (2026) or a Roman numeral (MMXXVI). Lowercase Roman letters are accepted.
- 2. Leave Direction on Auto-detect, or force Number → Roman or Roman → Number if you want the tool to treat the input one way only.
- 3. Read and copy the result. It appears as you type. Copy Result puts it on your clipboard and Clear empties the box.
- 4. Check the reference table. It lists the thirteen basic values, from 1 to 1000, plus the current year in Roman numerals.
The Rules of Standard Roman Numerals
- Seven letters. I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000. Values are added from left to right: XVI is 10 + 5 + 1 = 16.
- Subtraction. A smaller letter placed before a larger one is subtracted. Only six pairs are standard: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900).
- Repetition. I, X, C and M can be repeated up to three times in a row (III, XXX, CCC, MMM). V, L and D are never repeated.
- Read the largest first. Numerals are written from the highest place value down, so 1994 is M (1000) + CM (900) + XC (90) + IV (4) = MCMXCIV.
- No zero. The system has no symbol for zero, and the standard notation stops at MMMCMXCIX, which is 3999.
| Number | Roman numeral | Note |
|---|---|---|
| 4 | IV | Subtractive, not IIII |
| 49 | XLIX | XL + IX — not IL |
| 99 | XCIX | XC + IX — not IC |
| 444 | CDXLIV | CD + XL + IV |
| 1994 | MCMXCIV | M + CM + XC + IV |
| 2026 | MMXXVI | MM + XX + VI |
| 3999 | MMMCMXCIX | The largest standard numeral |
What the Converter Rejects
When you enter a Roman numeral, the tool works out its value and then writes that value back as a Roman numeral. If the result is not exactly what you typed, the numeral was malformed and you get an error. That is how IIII, VX, IC, IL, XM and VV are caught: each can be read as a number, but none is the standard way to write it. Numbers outside 1–3999, zero and decimals are also rejected.
Clock faces and some old inscriptions use IIII for 4, and medieval texts allow forms like IC for 99. This converter is strict on purpose, so it shows only the form that style guides and schools teach. Numerals above 3999 are written in some systems with a bar over the letter to multiply by 1,000; that is outside this tool.
Where Roman Numerals Are Used in Writing
They number the front matter of books — Chicago style sets preface and contents pages in lowercase Roman (i, ii, iii), and MLA cites such pages as printed — as well as outline levels (I, II, III), acts of a play, volumes and parts, monarchs and popes (Elizabeth II, Pius XII), event editions and the year in a film's copyright line. The converter outputs capitals; lower-case the result by hand for page numbers.
Which Tool Do You Need?
| You want to… | Use |
|---|---|
| Convert between Arabic numbers and Roman numerals | This converter |
| Spell a number as words (forty-two) | Number to Words |
| Write 1st, 2nd, 3rd or first, second, third | Ordinal Number Converter |
| Change a number between binary, decimal and hexadecimal | Number Base Converter |
| Number the lines of an outline | Outline Numberer |
Frequently Asked Questions
- How do I convert a number to Roman numerals?
- Type a whole number from 1 to 3999. The tool takes the largest Roman value that fits, writes its symbol, subtracts it and repeats. For 2026 that gives M, M, X, X, V, I: MMXXVI.
- Why is the range limited to 1–3999?
- Standard Roman numerals have no letter bigger than M (1000) and allow it to repeat only three times, so MMMCMXCIX (3999) is the largest number they can write. They also have no zero.
- Does the tool reject invalid Roman numerals?
- Yes. It re-encodes the value of what you typed and compares the two, so IIII, VX, IC and similar sequences are flagged as invalid instead of being quietly accepted.
- What is subtractive notation?
- Putting a smaller letter before a larger one subtracts it. The six standard pairs are IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). Only I, X and C can be subtracted, and only from the next two larger letters.
- How do I write the year in Roman numerals?
- Enter the year as a number. 2026 is MMXXVI, 2024 is MMXXIV and 1999 is MCMXCIX. The reference table also shows the current year in Roman numerals.
- Can I convert lowercase Roman numerals?
- Yes, the input is case-insensitive, so xiv is read as 14. The output is always in capitals; change it to lowercase yourself if you need it for front-matter page numbers.