Number → Roman Roman → Number Symbol Reference

Roman Numeral Converter

Convert any integer from 1 to 3999 into Roman numerals, or decode a Roman numeral string back to a number. See a full symbol-by-symbol breakdown with every result.

Input — What you entered
Result — Converted value
Length — Roman numeral length
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Number to Roman Numeral

Enter any whole number between 1 and 3999 to see its Roman numeral equivalent with a full symbol breakdown.

Results

Roman Numeral—
Breakdown—
How it works: Each symbol is chosen using the largest possible value at each step (greedy subtraction). Subtractive pairs like CM, XC, and IX represent values like 900, 90, and 9 with two characters.

Roman Numeral Symbol Reference

All 13 standard symbols used in the converter, from smallest to largest.

Symbol Value

Understanding Roman Numerals

A brief history of Roman numerals

Roman numerals developed in ancient Rome around 900–800 BCE, evolving from tally marks carved into wood or stone. The system was used throughout the Roman Empire for trade, record-keeping, and monumental inscriptions, and it remained the dominant numeral system in Europe well into the Middle Ages.

The seven core symbols — I, V, X, L, C, D, M — are believed to derive from hand gestures and early Etruscan numerals. Despite being superseded by Hindu-Arabic numerals for calculation, Roman numerals endure today in clocks, book chapters, movie sequels, and formal typography.

  • I, X, C, M are the primary additive symbols (powers of ten).
  • V, L, D are the midpoint symbols (five times a power of ten).
  • The system has no symbol for zero.

Subtractive notation explained

Classical Roman numerals use subtractive notation to avoid writing the same symbol more than three times in a row. When a lower-value symbol immediately precedes a higher-value symbol, you subtract rather than add.

There are exactly six valid subtractive pairs:

  • IV = 4 (I before V)
  • IX = 9 (I before X)
  • XL = 40 (X before L)
  • XC = 90 (X before C)
  • CD = 400 (C before D)
  • CM = 900 (C before M)

No other subtractive combinations are standard — for example, IL for 49 or VX for 5 are not used.

Where Roman numerals are used today

Despite their age, Roman numerals appear regularly in modern life:

  • Clock faces — traditional analog clocks often use Roman numerals for hours.
  • Book front matter — prefaces, forewords, and introductions use lowercase Roman numerals (i, ii, iii…) for page numbers.
  • Movie sequels and events — Super Bowl LVIII, Rocky IV, Star Wars Episode IX.
  • Monarchs and popes — King Charles III, Pope John Paul II.
  • Year marks on buildings — copyright notices and cornerstones often show the construction year in Roman numerals.
  • Outlines and lists — formal academic and legal outlines use Roman numerals for top-level sections.

Rules for writing Roman numerals

Follow these rules to write any number from 1 to 3999 correctly:

  • Repeat up to three times — I, X, C, and M may be repeated up to three times consecutively (III = 3, XXX = 30). V, L, and D are never repeated.
  • Largest values first — symbols are written from highest to lowest value, left to right, except for subtractive pairs.
  • Only six subtractive pairs — IV, IX, XL, XC, CD, CM. No other subtractions are valid.
  • One subtraction at a time — you cannot write IIX for 8; use VIII instead.
  • Maximum is 3999 — MMMCMXCIX. Numbers 4000 and above require extended notation not covered by the standard system.

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FAQ

What are Roman numerals?

Roman numerals are a numeral system from ancient Rome that uses letter combinations — I, V, X, L, C, D, and M — to represent values. Numbers are formed by combining symbols additively and, in certain cases, subtractively. For example, VIII = 8 (5+3) and IX = 9 (10−1).

How does subtractive notation work?

When a smaller-value symbol immediately precedes a larger-value symbol, you subtract the smaller from the larger. The six valid subtractive pairs are: IV (4), IX (9), XL (40), XC (90), CD (400), and CM (900). All other combinations are additive. For example, XIV = X + IV = 10 + 4 = 14.

What is the largest Roman numeral?

Using the standard system, the largest representable number is 3999, written as MMMCMXCIX. This breaks down as MMM (3000) + CM (900) + XC (90) + IX (9). The number 4000 would require MMMM, which violates the rule of repeating a symbol no more than three times.

Why is there no zero in Roman numerals?

Roman numerals evolved as a counting and tally system where the concept of "nothing" had no practical need for a symbol — you simply wrote nothing. Zero as a mathematical concept with its own symbol was developed in ancient India and reached Europe through Arabic scholarship centuries after the Roman numeral system was established.

How do you read a Roman numeral from left to right?

Work left to right, adding each symbol's value. When you encounter a smaller symbol immediately before a larger one, treat them as a subtractive pair and add the difference. For example, MCMXCIX: M (1000) + CM (900) + XC (90) + IX (9) = 1999. Use the converter above to check any Roman numeral instantly.