Understanding Roman Numerals
Roman numerals use seven letters — I, V, X, L, C, D, M — to represent numbers. They use both addition (e.g. VI = 6) and subtraction (e.g. IV = 4). This converter turns Arabic (decimal) numbers into Roman numerals and vice versa, for values from 1 to 3,999.
How Roman Numerals Work
Each letter has a fixed value: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000. Symbols are usually written from largest to smallest and added (e.g. MDC = 1600). When a smaller symbol appears before a larger one, it is subtracted: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900. That keeps numerals short and avoids writing four of the same symbol in a row.
Read left to right: add the value unless the next symbol is larger — then subtract.
Example: MCMXCVIII = 1000 + (1000−100) + (100−10) + 5 + 1+1+1 = 1998. The converter above accepts either an Arabic number (1–3999) or a valid Roman numeral and shows the other form.
Roman Numeral Reference Table
Quick reference for the seven symbols and common subtractive pairs. Values 1–3,999 cover most uses (years, outlines, clock faces).
| Symbol | Value | Example |
|---|---|---|
| I | 1 | III = 3 |
| IV | 4 | subtractive |
| V | 5 | VIII = 8 |
| IX | 9 | subtractive |
| X | 10 | XII = 12 |
| XL | 40 | subtractive |
| L | 50 | LXX = 70 |
| XC | 90 | subtractive |
| C | 100 | CC = 200 |
| CD | 400 | subtractive |
| D | 500 | DCC = 700 |
| CM | 900 | subtractive |
| M | 1000 | MM = 2000 |
Common Years in Roman Numerals
Dates on buildings, copyrights, and titles often use Roman numerals. A few examples:
Recent years
- 2024 = MMXXIV
- 2000 = MM
- 1999 = MCMXCIX
- 1984 = MCMLXXXIV
- 1776 = MDCCLXXVI
Classic numbers
- 100 = C
- 50 = L
- 14 = XIV
- 9 = IX
- 4 = IV
Roman Numeral FAQ
? What is the largest number in Roman numerals?
Classical Roman numerals have no single-letter form above M (1000). Numbers 1–3,999 are written with M, D, C, L, X, V, I and subtractive pairs. Larger numbers were sometimes written with a vinculum (overline) — e.g. M̅ for 1,000,000 — but this converter uses the standard range 1–3,999.
? Why is 4 written as IV and not IIII?
The subtractive rule: a smaller symbol before a larger one means subtract. So IV = 5 − 1 = 4, and IX = 10 − 1 = 9. This keeps numerals shorter. Clock faces sometimes use IIII for 4 for visual balance; both conventions exist.
? How do you convert Roman to Arabic?
Read left to right. If the current symbol’s value is less than the next symbol’s value, subtract it; otherwise add it. Example: MCM = 1000 + (1000−100) = 1900. The converter above does this automatically for any valid Roman numeral.
? Is there a Roman numeral for zero?
No. The Romans had no symbol for zero. Roman numerals represent positive integers only. This converter accepts numbers from 1 to 3,999; zero and negative numbers are outside the classical system.