Roman Numeral Converter

  • Select the conversion direction: Roman Numerals to Numbers or Numbers to Roman Numerals.
  • Enter a Roman numeral or an Arabic number accordingly.
  • Click the "Convert" button to perform the conversion.
  • The result will be displayed in the "Result" field.
  • You can see the detailed calculation formula in the "Calculation Details" section.
  • Your conversion history will be displayed in the "Calculation History" section.
  • Use the "Clear" button to clear the result and hide the calculation details.
  • Use the "Copy" button to copy the result to the clipboard.
Calculation History


    Roman numerals are a numerical system that dates back to ancient Rome. Although they have been largely replaced by the more efficient Arabic numeral system (1, 2, 3, etc.), Roman numerals still hold historical and symbolic significance. To bridge the gap between these two numerical systems, the “Roman Numeral Converter” tool was created.

    The Concept

    The concept behind the Roman Numeral Converter is straightforward: it translates between Arabic numerals and Roman numerals. To understand how this works, it’s essential to know the basic rules of Roman numerals:

    1. Roman numerals use seven symbols: I, V, X, L, C, D, and M, representing 1, 5, 10, 50, 100, 500, and 1000, respectively.
    2. Roman numerals are written from left to right, with the largest values placed to the left.
    3. If a smaller numeral appears before a larger one, it is subtracted. For example, IV represents 4 (5 – 1), and IX represents 9 (10 – 1).
    4. Numerals can be combined to represent larger numbers. For instance, XX is 20 (10 + 10), and MMMCMXCIV is 1994 (1000 + 1000 – 100 + 100 – 10 + 1 + 5 – 1).
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    Formulae and Algorithm

    Arabic to Roman Conversion

    To convert an Arabic numeral (integer) to a Roman numeral, the following algorithm can be used:

    1. Initialize an empty string to store the Roman numeral result.
    2. For each symbol in the Roman numeral system (M, D, C, L, X, V, I), from largest to smallest:
      • Repeat the following steps until the input number is less than the value of the current symbol:
        • Subtract the value of the symbol from the input number.
        • Append the symbol to the result string.
    3. Return the result string as the Roman numeral.

    Roman to Arabic Conversion

    Converting a Roman numeral back to an Arabic numeral is a bit more complex. It requires iterating through the Roman numeral from left to right and adding or subtracting values based on the current and next symbols. The algorithm can be summarized as follows:

    1. Initialize a variable to store the result (initialized to 0).
    2. Iterate through the Roman numeral string from left to right.
    3. If the current symbol’s value is less than the next symbol’s value, subtract it from the result.
    4. Otherwise, add the current symbol’s value to the result.
    5. Return the final result as the Arabic numeral.

    Example Calculations

    Arabic to Roman Conversion Examples:

    1. Input: 1994
      • Step 1: Initialize result as an empty string.
      • Step 2: M (1000) can be subtracted 1 time from 1994. Result: “M”
      • Step 2: CM (900) can be subtracted 1 time from 994. Result: “CM”
      • Step 2: XC (90) can be subtracted 1 time from 94. Result: “CMXC”
      • Step 2: IV (4) can be subtracted 4 times from 4. Result: “CMXCIV”
      • Step 3: The final result is “CMXCIV.”

    Roman to Arabic Conversion Examples:

    1. Input: “MMXXIV”
      • Step 1: Initialize result as 0.
      • Step 2: M (1000) is added to result: 1000.
      • Step 3: M (1000) is added to result: 2000.
      • Step 4: X (10) is subtracted from result: 1990.
      • Step 2: X (10) is added to result: 2000.
      • Step 3: IV (4) is subtracted from result: 1996.
      • Step 2: V (5) is added to result: 2001.
      • Step 3: The final result is 2001.
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    Real-World Use Cases

    The Roman Numeral Converter tool has several real-world use cases, including:

    1. Historical Documents: Researchers and historians encounter Roman numerals in historical documents. This tool can help them quickly convert these numerals to Arabic for better understanding.
    2. Clock Faces: Some clock faces use Roman numerals instead of Arabic ones. The converter can be used to read and set the time on such clocks accurately.
    3. Educational Purposes: In educational settings, students can use this tool to practice converting between Roman and Arabic numerals, improving their understanding of both systems.
    4. Numerical Analysis: In certain mathematical and scientific contexts, Roman numerals may be used for symbolic representation. The converter aids in performing numerical analysis with such symbols.


    The Roman Numeral Converter is a valuable tool that simplifies the conversion between Arabic and Roman numerals. Its algorithms and formulas allow for accurate and efficient translations, making it useful in various practical scenarios, from historical research to everyday life. While the Roman numeral system may no longer be widely used for complex calculations, its enduring presence in our culture ensures that tools like the Roman Numeral Converter remain relevant and helpful.


    1. Menninger, Karl. (1969). Number Words and Number Symbols: A Cultural History of Numbers. MIT Press.
    2. Ifrah, Georges. (2000). The Universal History of Numbers: From Prehistory to the Invention of the Computer. Wiley.
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