Roman Numerals Converter
Type a number or a numeral โ it works out which you meant. You get the answer, the pieces it is built from and the rule behind each one, plus a quiz and a printable chart.
Practice
Answer in either direction. Press Enter to check โ a wrong answer shows the right one and resets the streak.
Reference chart
Tap any entry to run it through the converter.
The seven letters
Every Roman numeral is spelled from seven letters: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1,000. Write them largest to smallest and add as you read โ MMXXVI is 1,000 + 1,000 + 10 + 10 + 5 + 1 = 2,026. There is no zero and no place value, so the position of a letter only matters through one exception: the subtractive pairs.
The four rules that decide every spelling
- Add as you go, biggest first. LXVII reads 50 + 10 + 5 + 1 + 1 = 67.
- A smaller letter in front means subtract. IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900. Those six pairs are the whole list โ IC and IM are not numerals.
- Only I, X, C and M may repeat, at most three times. This is why 4 is IV rather than IIII, and why 3,999 is the ceiling: MMMM is not allowed.
- V, L and D never repeat and are never subtracted. Two V's would just be an X, so 10 is written X.
Put together, the rules give exactly one correct spelling per number. This converter uses that standard form โ but it will still read a non-standard numeral like IIII (common on clock faces) and tell you what the usual spelling would be.
Where you still meet them
Roman numerals survive wherever a number needs to look formal or sit apart from ordinary digits: copyright years in film credits, cornerstones and clock faces, chapter and act numbers, monarch and pope names, Super Bowl editions, and the front matter page numbers of printed books. Reading them is a small skill with a long shelf life โ and the reason a converter beats memorising is that the rules are short enough to learn in an afternoon.
Frequently asked questions
How do you write 4 in Roman numerals?
IV โ a smaller letter in front of a larger one is subtracted, so IV is 5 โ 1. IIII appears on some clock faces but is not standard form.
What is 2026 in Roman numerals?
MMXXVI: MM (2,000) + XX (20) + VI (6).
Why is there no zero?
The system records totals rather than positions. Without place value there is nothing for a zero to hold, which is also why arithmetic on paper is so clumsy in Roman numerals.
What is the largest Roman numeral?
MMMCMXCIX = 3,999 in standard form. Above that, a bar over a numeral (the vinculum) multiplied it by 1,000 โ Vฬ meant 5,000.
Is IC a valid way to write 99?
No. Only I, X and C can be subtracted, and only from the next two larger symbols. 99 is XCIX โ 90 + 9.
How do I remember the order?
The mnemonic "My Dear Cat Loves Xtra Vitamins Intensely" runs M, D, C, L, X, V, I โ largest to smallest, the order you write them in.
More tools: prime number checker ยท fraction calculator ยท long division ยท rounding practice ยท times tables ยท printable worksheets ยท today's puzzle.