Roman Numeral Converter

Use these tools to convert between modern Arabic numbers and Roman numerals, for both single numbers and dates.

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Number/Numeral Converter

Enter a number (e.g., 2025) or a Roman numeral (e.g., MMXXV) to convert it. For large numbers, use an underscore `_` before a letter (e.g., `_V` for 5000).

Convert

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Date Converter

Enter a date using numbers or Roman numerals. Use `/`, `.`, `-`, or spaces as separators (e.g., `9/3/2025` or `IX/III/MMXXV`).

Convert Date

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How to Write Roman Numerals

• Letters are placed from left to right in order of value. Add the values together (e.g., `VI` = 5 + 1 = 6; `LXX` = 50 + 10 + 10 = 70).
• Subtractive Principle: A smaller numeral placed before a larger numeral is subtracted (e.g., `IV` = 5 - 1 = 4; `XC` = 100 - 10 = 90).
• The numerals `V`, `L`, and `D` are never repeated or subtracted.
• A numeral cannot be repeated more than three times in a row (e.g., `III` is 3, but `IIII` is not used).