Roman Numeral Converter
Convert between Roman numerals and decimal numbers. Supports values from 1 to 3,999.
Enter a number (1 to 3999) to convert it to Roman numerals, or paste a Roman numeral to see its decimal value. Supports the standard subtractive notation (IV, IX, XL, XC, CD, CM).
Standard Roman numerals use I, V, X, L, C, D, and M. The conventional range here is 1 to 3,999 because larger values need overline notation.
How Roman Numerals Work
Roman numerals use seven letters to represent numbers: I, V, X, L, C, D, and M. Unlike our decimal system where position determines value (the 3 in 300 means "three hundreds"), Roman numerals are additive, you combine symbols and add their values together. XVI is 10 + 5 + 1 = 16.
The clever part is the subtractive rule. When a smaller numeral appears before a larger one, you subtract instead of add. IV isn't 1 + 5 = 6, it's 5 − 1 = 4. This rule only applies to specific pairs: I before V or X, X before L or C, and C before D or M.
Standard Roman numerals max out at 3,999 (MMMCMXCIX). There's no symbol for zero, and numbers beyond 3,999 historically used an overline notation (a bar above a numeral multiplied its value by 1,000). This tool covers the standard range of 1 to 3,999.
Roman Numeral Reference Table
| Symbol | Value | Example | Combined Value |
|---|---|---|---|
| I | 1 | III | 3 |
| V | 5 | IV | 4 (5−1) |
| X | 10 | IX | 9 (10−1) |
| L | 50 | XL | 40 (50−10) |
| C | 100 | XC | 90 (100−10) |
| D | 500 | CD | 400 (500−100) |
| M | 1,000 | CM | 900 (1000−100) |
What this means for you: Memorise the six subtractive pairs (IV, IX, XL, XC, CD, CM) and you can read any Roman numeral. Everything else is just addition.
Subtractive Pairs Reference
Standard modern Roman numerals use only six subtractive pairs. A smaller symbol can be placed before a larger one only in these cases.
| Pair | Value | Expanded meaning | Example in a larger number |
|---|---|---|---|
| IV | 4 | 5 - 1 | XIV = 14 |
| IX | 9 | 10 - 1 | XIX = 19 |
| XL | 40 | 50 - 10 | XLII = 42 |
| XC | 90 | 100 - 10 | XCIX = 99 |
| CD | 400 | 500 - 100 | CDXL = 440 |
| CM | 900 | 1,000 - 100 | CMXC = 990 |
Pairs such as IL, IC, and VX are not standard notation, even if a simple left-to-right subtraction rule could assign them a number.
Decimal Place-Value Reference
Roman numerals do not use place value, but it helps to split a decimal number into thousands, hundreds, tens, and ones before converting.
| Decimal part | Roman pattern | Example |
|---|---|---|
| Thousands | M, MM, MMM | 3,000 = MMM |
| Hundreds | C, D, CM, CD | 900 = CM |
| Tens | X, L, XC, XL | 20 = XX |
| Ones | I, V, IX, IV | 6 = VI |
Common Roman Numerals You'll See
| Decimal | Roman | Where You'll See It |
|---|---|---|
| 4 | IV | Clock faces, chapter numbers |
| 9 | IX | Movie sequels, list numbering |
| 14 | XIV | Louis XIV, historical references |
| 50 | L | Super Bowl L, anniversaries |
| 100 | C | Centenary celebrations |
| 500 | D | Historical dates, monuments |
| 2024 | MMXXIV | Copyright notices, film credits |
| 2026 | MMXXVI | Current year |
Where Roman Numerals Still Appear
Film & Television
Movie copyright dates (© MMXXVI), sequel numbering (Rocky IV), and production credits still use Roman numerals as a tradition of formality.
Architecture & Monuments
Building cornerstones, memorial plaques, and clock faces use Roman numerals. Many clock faces famously use IIII instead of IV.
Academic & Legal
Book chapters, outline numbering (I, II, III), legal document sections, and academic paper divisions all use Roman numerals for hierarchical structure.
Events & Sports
The Super Bowl (LIX = 59), Olympic Games numbering, and royal succession (Elizabeth II, Charles III) all rely on Roman numerals.
Worked Example: Convert 2026 to Roman Numerals
To convert a year, split it into place-value parts, convert each part, then join the Roman pieces in descending order.
Thousands
2000 = MM
Hundreds
0 = no symbol
Tens
20 = XX
Ones
6 = VI
Put the pieces together: MM + XX + VI = MMXXVI.
Quick Year Conversions
Handy for copyright notices, film credits, and wedding invitations. The pattern is simple: MM = 2000, then add the last two digits in Roman numerals.
Regional and Style Context
Roman numerals are not metric or imperial units. They are a numeral notation, so the conversion is the same in the UK, US, Canada, Australia, and anywhere else using standard modern Roman numerals.
| Context | Typical style | Practical note |
|---|---|---|
| Book prelims | Lowercase Roman numerals | Pages may run i, ii, iii before chapter 1 starts |
| Monuments and cornerstones | Uppercase Roman numerals | Years are often shown as formal inscriptions |
| Clock faces | Often IIII instead of IV | This is a display tradition, not the standard converter form |
| Academic outlines | I, II, III for top-level sections | Lower levels often switch to letters or decimal numbers |
| Royal names and events | Uppercase suffix | Charles III, Elizabeth II, Super Bowl LIX |
Common Roman Numeral Mistakes
Repeating V, L, or D
V, L, and D are not repeated in standard notation. Write 10 as X, not VV, and 100 as C, not LL.
Using non-standard subtraction
49 is XLIX, not IL. Only I before V or X, X before L or C, and C before D or M are standard subtractive pairs.
Expecting a zero symbol
Standard Roman numerals have no zero. This tool starts at 1 and stops at 3,999.
Treating clock-face IIII as the converter standard
IIII appears on many clocks for visual balance. Standard numeral conversion uses IV for 4.
Going beyond 3,999 without notation rules
Larger historical numbers use marks such as overlines to multiply values. Plain M repetition is not enough for a clear modern standard.
Mixing lowercase style with value
Lowercase roman numerals are a typography choice. The value of iv is the same as IV.
Related Tools
Number Base Converter
Convert between binary, hex, octal, decimal
Random Number Generator
Generate cryptographically secure random numbers
Percentage Calculator
Calculate percentages and proportions
Binary Text Converter
Convert text to binary and back
Morse Code Translator
Translate text to and from Morse code
Date Difference Calculator
Calculate time between two dates
How to use this tool
Enter a decimal number (1 to 3,999) or a Roman numeral
The conversion happens instantly in the other field
Copy the result for use in documents, designs, or projects
Common uses
- Converting years to Roman numerals for copyright notices
- Decoding Roman numerals on clocks, buildings, and monuments
- Numbering chapters, sections, and outlines in academic writing
- Converting Super Bowl and event numbers
- Checking royal names, book volumes, and formal inscriptions
Share this tool
Frequently Asked Questions
How do Roman numerals work?
What is the largest Roman numeral?
Why are Roman numerals still used?
What does IV mean?
Why do clocks use IIII instead of IV?
Can I convert Roman numerals back to numbers?
What about zero in Roman numerals?
Are lowercase Roman numerals valid?
How do I write the current year?
What's the Super Bowl number system?
Can Roman numerals represent fractions?
Is the conversion instant?
Results are for general informational purposes only and should be checked before use. They are not professional advice. See our Disclaimer and Terms of Service.