Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals to numbers. Range 1-3999, standards-compliant.
Result
What are Roman numerals?
Roman numerals are a numeric system developed in ancient Rome that uses combinations of Latin letters (I, V, X, L, C, D, M) to represent numbers. They were the standard numeric system in Europe until the Hindu-Arabic numerals (0-9) replaced them around the 14th-15th centuries. Despite being less efficient for math, Roman numerals persist in many modern uses: clock faces, book chapter numbers (Chapter I, II, III), royal/papal/ruler names (Henry VIII, Pope John Paul II), Super Bowl numbering (LVII = 57), movie sequels (Rocky III, Star Wars Episode IX), copyright dates on old films, and as decorative or formal numbering. This converter handles both directions: numbers 1-3999 to Roman numerals, and Roman numerals back to numbers, with strict standard formatting.
How to use this tool
- Choose direction — Number → Roman (most common) or Roman → Number.
- Enter the value — For Number→Roman: 1 to 3999 (the standard range). For Roman→Number: any valid Roman numeral (I, V, X, L, C, D, M combinations).
- Read the result — Converted value shown immediately. The tool validates input - invalid Romans produce '- (Invalid)'.
Roman numeral rules
Symbols and values:
- I = 1
- V = 5
- X = 10
- L = 50
- C = 100
- D = 500
- M = 1000
Addition rule: When a smaller symbol comes AFTER a larger one, ADD it. VII = 5+1+1 = 7.
Subtraction rule: When a smaller symbol comes BEFORE a larger one, SUBTRACT. IV = 5-1 = 4. Only specific subtractions allowed:
- 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)
Repetition limit: Same symbol can appear up to 3 times in a row. III = 3, but IIII is INCORRECT (use IV instead).
Maximum: Standard Roman numerals go to 3999 = MMMCMXCIX. Beyond that requires special notation (overlines for multiplication) which is rarely used today.
Examples
- Year 2026: MMXXVI
- Year 1492 (Columbus): MCDXCII
- Year 1776 (US Independence): MDCCLXXVI
- Year 2000: MM
- Super Bowl LVII: 57
- Number 39: XXXIX
- Number 99: XCIX
- Number 3999 (max standard): MMMCMXCIX
- Number 444: CDXLIV
- Number 500: D
Tips & best practices
- Memorize the key symbols: I=1, V=5, X=10, L=50, C=100, D=500, M=1000
- Subtraction only with specific pairs: IV, IX, XL, XC, CD, CM - not just any 'smaller before larger'
- Read from left to right, adding values. If a smaller comes before a larger, subtract that smaller value
- No more than 3 of the same letter in a row - VIIII is wrong (should be IX)
- For dates, MM = 2000, MMI = 2001, MMXX = 2020, etc. - typical year representations
- Use uppercase for formal/traditional use (chapter headings, monarchs). Lowercase i, v, x, etc. is rare and informal
- For numbers above 3999, multiplication is shown with a bar over the symbol (overline) - rarely needed today
Limitations & notes
Standard Roman numerals only support 1-3999. Beyond requires special notation. Zero has no Roman numeral - Romans didn't have a zero concept. Negative numbers, fractions, and decimals don't exist in Roman numerals. The tool validates inputs strictly - non-standard forms like 'IIII' (instead of IV) are rejected. Some watch faces use 'IIII' for visual balance, but mathematically the correct form is IV.
Frequently Asked Questions
Why do some clocks use 'IIII' instead of 'IV'?
Tradition. Strictly, IV is correct. But many clockmakers use IIII for the 4 o'clock position to visually balance with VIII (8 o'clock) opposite it. Both 'IIII' and 'IV' have been used historically - clock face is a special case where aesthetic balance matters.
What's the biggest number in Roman numerals?
Standard: 3999 = MMMCMXCIX. The system has practical issues beyond that - you'd need 4 Ms in a row which violates the 'no more than 3 in a row' rule. Special bars/overlines extend the system to higher numbers but are rarely used.
How do you write zero in Roman numerals?
Romans didn't have zero - the concept of 'nothing' as a number came from India. Sometimes Latin 'N' (for 'nullus' - none) is used in medieval texts. For modern needs, just write '0' (Arabic numeral).
Can Roman numerals have decimals or fractions?
Fractions were sometimes written using duodecimal (base 12) - dots for twelfths. But Romans didn't have decimal fractions. The system only handles positive whole numbers.
Why are Super Bowls in Roman numerals?
Tradition started with Super Bowl I in 1967. Roman numerals give the event a 'classic / important' feel. Super Bowl 50 (2016) skipped to Arabic 'Super Bowl 50' because 'L' alone wasn't visually impressive. Returned to Roman in subsequent years.
Is 'VL' or 'IL' valid for 45 or 49?
No - subtraction is only allowed with specific pairs. VL (45) and IL (49) are NOT valid - V can't precede L, I can't precede L. Correct: XLV = 45, XLIX = 49.
Why is 1990 MCMXC and not MCMLLL?
Repetition limit: no more than 3 same symbols in a row (LLL invalid). For 90, use XC (100 - 10 = 90). So 1990 = M (1000) + CM (900) + XC (90) = MCMXC.