Roman Numeral Converter
Convert a number to Roman numerals.
Results update as you type.
How it works
Roman numerals are the letter-based number system of ancient Rome, still used today for clock faces, book chapters, movie sequels, and monument dates, and this converter turns an ordinary number into its Roman form. You enter a whole number from 1 to 3999, and it returns the Roman numeral. The system uses seven symbols with fixed values: I for one, V for five, X for ten, L for fifty, C for one hundred, D for five hundred, and M for one thousand. Numbers are formed by combining these from largest to smallest and adding their values, so MMXXIV is 1000 plus 1000 plus 10 plus 10 plus 4, or 2024. A key rule is subtractive notation: rather than writing four identical symbols, a smaller symbol placed before a larger one is subtracted, so 4 is IV, 9 is IX, 40 is XL, and 90 is XC. The converter applies these standard rules to produce the conventional modern form. The range is limited to 1 through 3999 because the basic system has no symbol for zero or for values of four thousand and above without special notation like overlines. Students, designers, and anyone decoding a date or numbering scheme use this. Enter a number to convert it to Roman numerals.
Greedy subtraction using I, V, X, L, C, D, M
Roman numerals are built from seven symbols: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500, and M is 1000. The calculator repeatedly subtracts the largest possible value, appending its symbol, and uses subtractive pairs like IV for 4 and IX for 9 to avoid four repeated symbols. This produces the standard modern form.
Source:Number systems
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Worked example
How to use this calculator
- 1
Enter your values
Enter number (1–3999).
- 2
Adjust the options
Fine-tune any options to match your situation.
- 3
Read your result
Roman numeral updates instantly as you type — no button to press.
Frequently asked questions
How do Roman numerals work?
Roman numerals use seven letters with set values: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500, and M is 1000. Numbers combine these from largest to smallest, adding their values, with subtractive pairs like IV for 4 and IX for 9 to avoid repeating a symbol four times.
What is subtractive notation?
Subtractive notation places a smaller symbol before a larger one to subtract it, avoiding four repeated symbols. So 4 is written IV, one before five, rather than IIII, and 9 is IX. Similarly 40 is XL, 90 is XC, 400 is CD, and 900 is CM. This keeps Roman numerals shorter and is the standard modern convention.
Why is the range limited to 3999?
The basic Roman numeral system, using only the standard letters, can express up to 3999 as MMMCMXCIX. Larger numbers require special notation, such as an overline over a symbol to multiply it by a thousand, which is not part of the everyday letter system. So this converter covers the common range of 1 to 3999.
Is there a Roman numeral for zero?
No, the Roman numeral system has no symbol for zero. It was designed for counting and recording quantities, where zero was not needed as a placeholder. The concept of zero as a number came later from other mathematical traditions. This is one reason the system is not used for arithmetic today.
Where are Roman numerals still used?
Roman numerals appear on clock and watch faces, in book chapter and page numbering, for movie and event sequels like Super Bowl LVIII, in the names of monarchs and popes, on building cornerstones and monuments to mark dates, and in outlines. They add a classical, formal feel and remain widely recognized despite decimal numbers dominating.