Roman Numeral Converter
Convert Arabic numbers to Roman numerals and Roman numerals back to Arabic numbers instantly. Perfect for historians, students, designers, and anyone working with classical numbering systems.
Conversion Type
Conversion Result
Ready to Convert
Enter a number or Roman numeral and click "Convert Now"
Roman Numeral Chart
| Arabic | Roman | Arabic | Roman |
|---|---|---|---|
| 1 | I | 50 | L |
| 4 | IV | 90 | XC |
| 5 | V | 100 | C |
| 9 | IX | 400 | CD |
| 10 | X | 500 | D |
| 40 | XL | 900 | CM |
| 1000 | M | 3999 | MMMCMXCIX |
Note: Roman numerals use subtractive notation (IV = 4, not IIII)
Quick Converter
Basic Rules
- I, X, C, M can repeat up to 3 times
- V, L, D cannot repeat
- Subtractive notation: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900)
- Read from left to right, larger to smaller values
- No zero in Roman numeral system
- No negative numbers in Roman numerals
Historical Fact
Roman numerals originated in ancient Rome and were used throughout the Roman Empire.
The system remained common in Europe until the 14th century when Arabic numerals gradually replaced them.
What is a Roman Numeral Converter?
A Roman numeral converter is a specialized tool that translates between the Arabic numeral system (1, 2, 3, etc.) and the Roman numeral system (I, V, X, etc.). This ancient numbering system, developed in ancient Rome, uses combinations of letters from the Latin alphabet to represent values. Unlike modern positional notation, Roman numerals use additive and subtractive principles.
Our Roman numeral converter supports bidirectional conversion, handling numbers up to 3,999,999 using extended notation with vinculum (bars over numerals). It strictly follows classical Roman numeral rules while providing modern convenience, educational breakdowns, and historical context.
How to Use This Roman Numeral Converter
Our converter offers the most intuitive Roman numeral conversion experience available. Follow these simple steps:
- Select Conversion Direction: Choose whether to convert "Number to Roman" or "Roman to Number" using the top buttons.
-
Enter Your Value:
- For numbers: Enter any Arabic number from 1 to 3,999,999
- For Roman numerals: Enter valid Roman characters (I, V, X, L, C, D, M) in uppercase
- Quick Entry Options: Use the quick buttons for common values (I, V, X, etc.) or historical dates.
- Convert: Click the "Convert Now" button to instantly see your conversion.
- Review Results: Examine the detailed conversion, including breakdown and validation information.
- Learn: Use the Roman numeral chart and rules sidebar to understand the conversion process.
Understanding the Roman Numeral System
Basic Symbols
| Roman | Value | Latin Name |
|---|---|---|
| I | 1 | Unus |
| V | 5 | Quinque |
| X | 10 | Decem |
| L | 50 | Quinquaginta |
| C | 100 | Centum |
| D | 500 | Quingenti |
| M | 1,000 | Mille |
Subtractive Notation
Roman numerals use subtractive notation for efficient representation. Instead of writing IIII for 4, Romans wrote IV (5-1).
Why Use This Roman Numeral Converter?
Roman numerals continue to be relevant in modern times, and our converter provides essential benefits:
Instant Conversion
Convert numbers up to 3,999,999 in milliseconds with 100% accuracy.
Educational
Detailed breakdowns help students learn Roman numeral rules and patterns.
Historical Accuracy
Follows classical Roman rules with support for vinculum notation.
Validation
Validates Roman numeral input and provides error correction suggestions.
Modern Applications of Roman Numerals
| Field | Usage | Examples |
|---|---|---|
| Clocks & Watches | Traditional timepiece numbering | I, II, III, IV on clock faces |
| Monuments & Buildings | Construction dates and cornerstones | MDCCLXXVI (1776) on U.S. monuments |
| Book Publishing | Front matter page numbering | Preface, table of contents pages |
| Movie Industry | Film sequels and copyright years | Star Wars: Episode IV, Rocky V |
| Numbering Systems | Outlines, lists, and hierarchies | I., II., III. in documents |
| Academic | Chemistry, music, and linguistics | Chemical compounds, chord names |
Roman Numeral Conversion Examples
Step-by-Step Conversion: 1984
Frequently Asked Questions (FAQ)
What is the largest number this converter can handle?
Our converter can handle numbers up to 3,999,999. For numbers beyond 3,999 (the classical Roman limit), we use vinculum notation (bars over numerals) where a bar multiplies the value by 1,000. For example, V̅ = 5,000, X̅ = 10,000, and M̅ = 1,000,000. The practical limit is 3,999,999 which would be M̅M̅M̅C̅M̅X̅C̅I̅X̅CMXCIX.
Why do clocks often show IIII instead of IV for 4?
This is a historical convention known as the "clockmaker's four" or "watchmaker's four." There are several theories: symmetry with VIII on the opposite side, tribute to Roman god Jupiter (IV being the first letters of Jupiter in Latin), or simply aesthetic balance. Our converter follows standard classical Roman numerals (IV for 4), but we acknowledge the IIII convention for historical accuracy.
How do I convert years with BC/AD?
Roman numerals themselves don't indicate BC or AD - these are separate designations. For BC years, convert the number normally and add "BC" after (e.g., 44 BC = XLIV BC). For AD years, you can either write the numeral alone or add "AD" before (e.g., AD 1066 = MLXVI). The converter focuses on the numeral conversion only; the era designation is added separately based on context.
Are lowercase Roman numerals valid?
In classical Roman times, all writing was typically in what we now call uppercase. Lowercase Roman numerals (i, v, x, etc.) are a modern convention. Our converter accepts both uppercase and lowercase input but converts everything to uppercase for consistency. The classical form is uppercase, which is what we display in results. In formal contexts and historical documents, uppercase is preferred.
Can Roman numerals represent fractions or decimals?
The Roman numeral system did have symbols for fractions, but they are not commonly used today. The most common fraction was "S" for 1/2 (semis). Other fractions used dots or specific symbols. Our converter does not support fractional Roman numerals as they are extremely rare in modern usage. For decimal numbers, we recommend converting the whole number part only or using Arabic numerals.
What are common mistakes when writing Roman numerals?
Common errors include: repeating V, L, or D (only I, X, C, M can repeat); incorrect subtractive combinations (IL for 49 instead of XLIX); mixing additive and subtractive incorrectly; placing smaller values before larger ones in wrong contexts. Our converter validates input and provides helpful error messages to correct these common mistakes. The "Roman Numeral Rules" section in the sidebar clearly outlines all valid patterns.
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