Roman Numeral Converter
Convert a number (1-3999) to Roman numerals.
Input sheet
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Roman numerals still show up on clock faces, movie copyright dates, Super Bowls, and book chapters. This converter turns any whole number from 1 to 3999 into its correct Roman numeral form.
How it works
Greedily subtracts the largest Roman value (including subtractive pairs like IV and CM) until the number reaches zero.
The system uses seven letters (I, V, X, L, C, D, M) and a subtractive rule: a smaller symbol placed before a larger one subtracts, so 4 is IV and 90 is XC rather than IIII or LXXXX.
The converter works greedily, repeatedly subtracting the largest possible value — including subtractive pairs like CM (900) and XL (40) — until nothing remains, which always yields the standard shortest form.
Repeatedly take the largest Roman value (M=1000, CM=900, D=500, CD=400, C=100, XC=90, L=50, XL=40, X=10, IX=9, V=5, IV=4, I=1) that fits and append its symbol until the number reaches zero.
Worked examples
The number 2026. → MMXXVI (6 characters).
2000 = MM, 20 = XX, 6 = VI.
The number 49. → XLIX.
40 = XL and 9 = IX — note it is not IL, which is not a valid form.
Tips & gotchas
- The classic 'rule of four' limits any symbol to three repeats in a row; the fourth is written subtractively (so 40 is XL, not XXXX).
- There is no zero and no negative in standard Roman numerals — the practical range here is 1 to 3999.
- On many clock faces 4 appears as IIII rather than IV; that is a traditional stylistic choice, not the standard mathematical form this tool uses.
- To read a numeral, add symbols left to right but subtract any smaller symbol that sits before a larger one.
FAQ
Why does it stop at 3999?
Standard Roman numerals only go to 3999 (MMMCMXCIX). Larger numbers historically used a bar over a symbol to multiply it by 1000, a notation that is rarely needed today.
How do I write the current year?
Break the year into thousands, hundreds, tens, and ones and convert each — for example 2026 becomes MM + XX + VI = MMXXVI.
Can I convert a numeral back to a number?
Yes by hand: sum the values, subtracting any symbol that precedes a larger one. This tool currently converts numbers into numerals.
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