Roman Numeral Converter
Convert numbers from 1 to 3999 into Roman numerals.
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Enter any whole number from 1 to 3999 and this converter writes it in Roman numerals, for example 2026 as MMXXVI. It converts in one direction, from ordinary numbers to Roman numerals.
The seven symbols
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1000 |
Symbols are normally written from largest to smallest and added together. When a smaller symbol comes before a larger one, it is subtracted instead: IV is 4 and XC is 90.
How the conversion works: 1947 step by step
The converter repeatedly takes the largest value that still fits, from a list that includes the six subtractive pairs (CM 900, CD 400, XC 90, XL 40, IX 9, IV 4):
- 1947 − 1000 = 947 → M
- 947 − 900 = 47 → CM
- 47 − 40 = 7 → XL
- 7 = 5 + 1 + 1 → VII
Result: MCMXLVII. Similarly, 1994 is MCMXCIV and 3999, the largest value accepted, is MMMCMXCIX.
To check any result, read it back from left to right, adding each symbol and subtracting one that sits before a larger symbol: MMXXVI is 1000 + 1000 + 10 + 10 + 5 + 1 = 2026. The converter outputs capitals, but lowercase is equally valid and means the same value; page numbers conventionally use i, ii, iii and iv, while chapter headings use capitals.
The subtraction rules people get wrong
- Only I, X and C are used to subtract, and only from the next two symbols up: I before V or X, X before L or C, C before D or M.
- So 49 is XLIX (40 + 9), not IL, and 99 is XCIX, not IC.
- 1990 is MCMXC, not MXM.
- No symbol repeats more than three times in a row in standard form, which is why 4 is IV. Many clock faces use IIII instead, a long-standing design tradition rather than an error.
Why the limit is 3999
Standard Roman numerals have no symbol above M, so 4000 would need MMMM, which breaks the three-in-a-row rule. The Romans wrote large numbers with a bar over a numeral to multiply it by 1000, but that notation is not part of the standard modern form. There is also no Roman numeral for zero, so the converter asks for a number from 1 upwards and rounds decimals down.
Where Roman numerals still appear
- School classes: Class X and Class XII board exams in India.
- Book front matter: preface and contents pages are often numbered i, ii, iii.
- Names of monarchs and popes, such as Louis XIV or George V.
- Film credits and building foundation stones, which often give the year this way.
- Outlines and legal documents, for numbering sections and clauses.
For a date, convert each part separately: 15 August 1947 becomes XV · VIII · MCMXLVII. To spell a number out in English words instead, try the number to words converter.