Roman Numerals Converter

About Roman Numerals

Roman numerals are that old number system you see on clock faces, movie copyright dates, and chapter numbers in books. They've been around since ancient Rome, and even though we use regular numbers (Arabic numerals) for pretty much everything now, Roman numerals stuck around for certain uses.

The system uses letters from the Latin alphabet to represent numbers. I equals 1, V equals 5, X equals 10, L equals 50, C equals 100, D equals 500, and M equals 1000. You combine these letters to make other numbers. Three ones (III) is 3. A five and a one (VI) is 6. Sounds simple, but it gets trickier with the subtraction rules.

Here's where it gets interesting—sometimes a smaller number before a larger one means you subtract instead of add. IV is 4 (5 minus 1), not 6. IX is 9 (10 minus 1). XL is 40 (50 minus 10). XC is 90 (100 minus 10). CD is 400 (500 minus 100). CM is 900 (1000 minus 100). These subtraction combinations only work with specific pairs, which makes Roman numerals kind of a pain to work with compared to our decimal system.

You'll still see Roman numerals in a bunch of places. Movie copyright dates at the end of films use them—that MCMLXXXIV you see is 1984. Clock faces sometimes have Roman numerals instead of regular numbers. Book chapters are often numbered with Roman numerals, especially in older books or formal publications. Volume numbers in book series use them too.

Monarch names and popes use Roman numerals to differentiate people with the same name. Queen Elizabeth II, Pope John Paul II—the Roman numeral tells you this is the second person with that name. Same idea with sequels sometimes—Rocky II, Rocky III, though movies tend to just use regular numbers now.

Historical dates sometimes appear in Roman numerals, especially on monuments, buildings, or formal documents. That building cornerstone that says MDCCCXC means 1890. Plaques and inscriptions often use Roman numerals for that classical, formal look.

Outlines and lists sometimes use Roman numerals for organization. I, II, III for main sections, then A, B, C for subsections. Legal documents, academic papers, and formal writing often structure things this way. It gives a hierarchical feel that regular numbers don't quite match.

Event names use Roman numerals too. The Super Bowl is numbered with Roman numerals—Super Bowl LVIII is the 58th one. The Olympic Games do the same thing. World Wars are sometimes written as World War I and World War II, though you'll see both Roman and regular numerals for those.

Music theory uses Roman numerals for chord analysis. Major chords get uppercase numerals (I, IV, V), minor chords get lowercase (ii, iii, vi). Musicians use this system to analyze chord progressions and talk about music in a key-independent way.

Converting between Roman numerals and regular numbers can be tricky, especially for larger numbers. 1984 is MCMLXXXIV—that's 1000 (M) + 900 (CM) + 80 (LXXX) + 4 (IV). Working it out manually takes time, and it's easy to make mistakes with all those subtraction rules.

People use Roman numerals today mostly for tradition and aesthetics. They look formal and classical. But they're not practical for math or calculations—try doing arithmetic with them and you'll see why we switched to the decimal system. They're purely symbolic now, used when you want that traditional, formal appearance.

If you need to convert Roman numerals to regular numbers (or vice versa), this converter handles it for you. No need to remember all those rules or work out the conversions manually. Just type in what you have, and it gives you the other format instantly. Whether you're trying to figure out what MCMLXXXIV means or you need to write 2024 in Roman numerals, this tool makes it easy.

Basic Roman Numerals

• I = 1
• V = 5
• X = 10
• L = 50
• C = 100
• D = 500
• M = 1000

Rules for Roman Numerals

1. Numbers are formed by combining symbols and adding their values
2. Symbols are generally placed in order of value, starting with the largest values
3. When a smaller value precedes a larger value, the smaller value is subtracted from the larger value
4. The symbols "I", "X", "C", and "M" can be repeated three times in succession
5. The symbols "V", "L", and "D" are never repeated

Common Combinations

• IV = 4 (5-1)
• IX = 9 (10-1)
• XL = 40 (50-10)
• XC = 90 (100-10)
• CD = 400 (500-100)
• CM = 900 (1000-100)

Usage Examples

• Historical dates (e.g., MCMLXXX = 1980)
• Chapter numbers in books
• Clock faces
• Movie copyright dates
• Names of monarchs and popes