About the Roman Numeral Converter
This Roman numeral converter works in both directions. Type a whole number between 1 and 3,999 to get its Roman numeral (for example 2026 becomes MMXXVI), or switch the mode and type a numeral such as MCMXCIV to see the number it stands for. The breakdown table shows exactly which symbols make up the answer, so you can learn the pattern rather than just copy the result.
It is handy for reading dates on buildings, film credits and clock faces, writing tattoo or engraving dates, numbering book chapters and outlines, checking homework, or decoding Super Bowl and event numbers. The converter also validates what you type: if a numeral is written in a non-standard way (such as IIII or IC) it tells you the value it adds up to and shows the correct standard spelling.
Standard Roman numerals only go up to 3,999 (MMMCMXCIX) because there is no symbol for 5,000 in the everyday system; larger values traditionally used a bar over a letter to multiply it by 1,000. There is also no Roman numeral for zero or for negative numbers.
How to use the roman numeral converter
- 1Choose whether you are converting a number to Roman numerals or the other way round.
- 2Type a whole number from 1 to 3,999, or a Roman numeral using I, V, X, L, C, D and M.
- 3Read the result and the symbol-by-symbol breakdown.
- 4If you entered a numeral, check the note — it flags non-standard spellings and shows the correct form.
Formula and method
To write a number in Roman numerals, repeatedly take the largest value from the list M, CM, D, CD, C, XC, L, XL, X, IX, V, IV, I that still fits, write its symbol and subtract it, until nothing is left. This “greedy” method always produces the standard spelling.
To read a numeral, go left to right and add each symbol’s value — except when a smaller symbol sits directly before a larger one, in which case it is subtracted (the I in IV, the C in CM). Only I, X and C are used subtractively, a symbol is never repeated more than three times in a row, and V, L and D are never repeated. The converter re-encodes your input to check it follows these rules.
- I, X, C, M
- Powers of ten: 1, 10, 100, 1,000 (may repeat up to three times)
- V, L, D
- Fives: 5, 50, 500 (never repeated)
- Subtractive pair
- A smaller symbol before a larger one is subtracted, e.g. IX = 9
Worked examples
Write the year 2026
2026 = 1000 + 1000 + 10 + 10 + 5 + 1, so it is written MM (2000) + XX (20) + VI (6) = MMXXVI.
Decode MCMXCIV
M = 1000, CM = 900 (100 before 1000 is subtracted), XC = 90 and IV = 4. Adding 1000 + 900 + 90 + 4 gives 1994.
Largest standard numeral: 3999
3999 = 3000 + 900 + 90 + 9, which becomes MMM + CM + XC + IX = MMMCMXCIX. One more (4000) would need a fourth M or a barred numeral, so 3999 is the usual upper limit.
Non-standard clock-face IIII
Many clock faces show 4 as IIII. It still adds up to 4, but the standard spelling is IV, which the converter shows alongside the value.
Frequently asked questions
How do you write 2026 in Roman numerals?+
2026 is MMXXVI: MM for 2000, XX for 20 and VI for 6. Years are converted exactly like any other number.
Why do Roman numerals stop at 3999?+
The largest single symbol is M (1,000) and a symbol may repeat at most three times, so MMMCMXCIX (3,999) is the largest standard numeral. Romans wrote bigger numbers with a bar (vinculum) over a letter to multiply it by 1,000.
Is there a Roman numeral for zero?+
No. The Roman system has no symbol for zero and no way to write negative numbers or fractions in everyday use. Medieval scholars sometimes used the word “nulla” or the letter N for zero.
Why do some clocks use IIII instead of IV?+
Using IIII for 4 is a long clock-making tradition, often explained as better visual balance with VIII on the other side of the dial. It is non-standard but widely accepted on clock faces.
Which letters can be subtracted in Roman numerals?+
Only I, X and C are placed before a larger symbol to subtract: I before V or X, X before L or C, and C before D or M. So 99 is XCIX, not IC, and 49 is XLIX, not IL.