Roman Numeral Converter
Convert between Arabic numerals (1-3999) and Roman numerals (I-MMMCMXCIX)
Roman Numeral Reference:
1
5
10
50
100
500
1000
Examples:
Understanding Roman Numerals
Roman numerals originated in ancient Rome and were used throughout the Roman Empire. Though largely replaced by Arabic numerals, they're still used for clock faces, book chapters, movie sequels, and formal documents.
The Seven Basic Symbols
Roman numerals use seven letters from the Latin alphabet:
- I = 1 (unus)
- V = 5 (quinque)
- X = 10 (decem)
- L = 50 (quinquaginta)
- C = 100 (centum)
- D = 500 (quingenti)
- M = 1000 (mille)
Additive Principle
In general, numerals are added from left to right in descending order. For example, XVII = 10 + 5 + 1 + 1 = 17.
Subtractive Principle
When a smaller numeral appears before a larger one, it's subtracted. This applies in specific cases:
- IV = 4 (5 - 1)
- IX = 9 (10 - 1)
- XL = 40 (50 - 10)
- XC = 90 (100 - 10)
- CD = 400 (500 - 100)
- CM = 900 (1000 - 100)
Limitations
Standard Roman numerals can only represent numbers from 1 to 3999. Numbers 4000 and above traditionally required special notation like vinculum (overline) to multiply by 1000.
Modern Uses
- Clock faces: IV or IIII for 4
- Outlines: I, II, III for main sections
- Movie sequels: Rocky III, Star Wars Episode IV
- Super Bowl: Super Bowl LVIII
- Monarchs: Queen Elizabeth II
- Year dates: MMXXIV = 2024
Worked Example: Converting 1994
To convert 1994, break it into place values and convert each one: 1000 = M, 900 = CM, 90 = XC, and 4 = IV. Reading them in order gives MCMXCIV. The converter shows this same step-by-step breakdown for any number you enter, which makes it easy to see where each symbol comes from.
Common Year Conversions
- 1776 = MDCCLXXVI
- 1900 = MCM
- 1999 = MCMXCIX
- 2000 = MM
- 2025 = MMXXV
Frequently Asked Questions
How do I write 2026 in Roman numerals?+
2026 is MMXXVI: MM for 2000, XX for 20, and VI for 6. The converter shows this breakdown step by step, so you can see exactly which symbols correspond to each place value of the number.
Why do Roman numerals only go up to 3999?+
Standard notation never repeats a symbol more than three times, and M (1000) is the largest symbol, so MMMCMXCIX (3999) is the highest expressible value. Larger numbers historically used a vinculum, an overline that multiplies a numeral by 1000, but that notation is not part of the standard seven-symbol system this converter uses.
Is IIII or IV correct for the number 4?+
IV is the correct subtractive form in standard modern usage. However, many clock faces traditionally use IIII for visual balance with VIII on the opposite side of the dial, a convention dating back centuries. The converter always outputs the standard subtractive form.
Why is XM not a valid way to write 990?+
Subtractive pairs are restricted: I can only precede V and X, X can only precede L and C, and C can only precede D and M. So 990 must be written CMXC (900 + 90), not XM. The converter validates your input and rejects malformed numerals like IC, XM, or VX.
Is this Roman numeral converter free and does it work on mobile?+
Yes. It is free, requires no sign-up, and runs entirely in your browser, so conversions are instant and nothing is sent to a server. The layout is responsive and works on phones, tablets, and desktop computers.
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