Roman Numeral Converter

Convert between Roman numerals and Arabic numbers.

Result
MMXXIV

How to Use This Calculator

Convert your birth year to Roman numerals. For example, 1990. Select "Number to Roman", enter 1990, and click Convert. The result is MCMXC. How does that work? M = 1000, CM = 900 (100 before 1000), and XC = 90 (10 before 100), so MCMXC = 1000 + 900 + 90 = 1990. Now try decoding "MMXXIV" — that's 2024 (1000+1000+10+10+1+5, with IV being 4). Switch to "Roman to Number", enter MMXXIV, and you get 2024. Try some others: 1776 (American independence) becomes MDCCLXXVI, and 2025 becomes MMXXV. The converter handles any number from 1 (I) to 3999 (MMMCMXCIX).

About Roman Numeral Converter

The Roman Numeral Converter converts between Arabic numbers (1–3999) and Roman numerals. You can type a number to get its Roman representation (e.g., 2024 becomes MMXXIV) or enter a Roman numeral to decode it back to an integer. The conversion uses the standard subtractive notation system — where 4 is IV (not IIII), 9 is IX, 40 is XL, 90 is XC, 400 is CD, and 900 is CM — which is the modern standard for Roman numerals. This tool is handy for historians reading ancient dates, for students studying Roman history or Latin, for movie enthusiasts deciphering copyright years in film credits, for clock and watch enthusiasts, and for anyone encountering Roman numerals in outlines, book chapters, or sporting event numbering (like the Super Bowl). The bidirectional conversion makes it easy to switch between numeric and symbolic representations. Understanding Roman numerals also provides insight into how ancient civilizations performed arithmetic without a place-value system, making this converter both a practical utility and a window into mathematical history.

When to Use This Calculator

Movie & TV Credits: Film copyright years at the end of movie credits are often in Roman numerals. MDCCCCXLVIII might look confusing, but the standard form is the more compact MCMXLVIII = 1948. Use this converter whenever you see a Roman numeral in credits and want to know the actual year.

Historical Documents: Old books, monuments, and official documents use Roman numerals for dates. The U.S. Declaration of Independence is dated "MDCCLXXVI" (1776). Building cornerstones often have Roman numeral dates. Instead of puzzling them out, just type them into this converter.

Sports & Events: The Super Bowl uses Roman numerals — Super Bowl LVIII was 58, and Super Bowl LIX will be 59. Olympic Games sometimes use them too. If you see an event numbered in Roman numerals and aren't sure what number it is, the converter gives you an instant answer.

Frequently Asked Questions

Why is 1999 written as MCMXCIX and not MIM?

Standard Roman numeral rules only allow subtraction for powers of 10 (I, X, C, M) and their halves (V, L, D). MCMXCIX breaks down as M (1000) + CM (900) + XC (90) + IX (9) = 1999. While MIM (1000 + 999) would be shorter, IM isn't a valid subtractive pair because you can't subtract I from M directly.

Why is 4 written as IV instead of IIII?

IV uses subtractive notation: I (1) before V (5) means 5 - 1 = 4. This became the standard because it's shorter and clearer than IIII. The subtractive principle applies to powers of 10 (I, X, C) placed before the next two higher symbols: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900).

How do I convert large numbers to Roman numerals?

For numbers up to 3999, the converter handles them automatically using standard symbols. For example, 2024 = MMXXIV. For numbers beyond 3999, traditional Roman numerals used a vinculum (a bar over a symbol multiplies it by 1000), but this converter supports the standard range of 1-3999.

What is the largest number that can be written in Roman numerals?

Using standard symbols without special notation, the maximum is 3999 = MMMCMXCIX. Ancient Romans could represent larger numbers using a vinculum (bar over a symbol multiplies by 1000), so V̅ = 5000, X̅ = 10,000, etc. However, the converter supports the standard range of 1-3999.

Are there rules for subtracting in Roman numerals?

Yes, strict rules apply: only I, X, C can be used for subtraction. I can only precede V or X (IV=4, IX=9). X can only precede L or C (XL=40, XC=90). C can only precede D or M (CD=400, CM=900). Only one smaller numeral can be placed before a larger one for subtraction.