Roman Numeral Converter — Numbers to Roman Numerals & Back
Roman numerals appear everywhere — movie release years, Super Bowl numbers, clock faces, chapter headings, and legal document outlines. Our free online Roman Numeral Converter instantly converts any decimal number to Roman numerals and any Roman numeral string back to a decimal number. No sign-up, 100% private, works offline.
What Are Roman Numerals?
Roman numerals are a numeral system that originated in ancient Rome and remained the standard for writing numbers throughout Europe well into the Middle Ages. The system uses combinations of seven Latin letters to represent values:
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1000 |
Numbers are formed by combining these symbols according to additive and subtractive rules. For example, IV means 4 (5 minus 1), and IX means 9 (10 minus 1).
Subtractive Notation Rules
The six subtractive combinations used in standard Roman numerals are:
| Combination | Value | Meaning |
|---|---|---|
| IV | 4 | 5 − 1 |
| IX | 9 | 10 − 1 |
| XL | 40 | 50 − 10 |
| XC | 90 | 100 − 10 |
| CD | 400 | 500 − 100 |
| CM | 900 | 1000 − 100 |
A smaller value placed before a larger value means subtraction. A smaller value placed after a larger value means addition: VIII = 8 (5 + 1 + 1 + 1).
How to Use the Converter
- Number to Roman: Type any integer from 1 to 3999 in the input field — the Roman numeral equivalent appears instantly
- Roman to Number: Switch to decode mode, type a Roman numeral string (e.g.,
MCMXCIX) — the decimal number appears immediately - Copy: Click copy to grab the output
Common Roman Numeral Examples
| Decimal | Roman | Where You See It |
|---|---|---|
| 4 | IV | Clock faces |
| 9 | IX | Super Bowl IX |
| 14 | XIV | Chapter XIV |
| 40 | XL | XL (extra large) |
| 49 | XLIX | Super Bowl XLIX |
| 100 | C | Century mark |
| 1999 | MCMXCIX | Movie copyright years |
| 2026 | MMXXVI | Year in monuments |
Frequently Asked Questions
What is the largest number you can write in Roman numerals?
Standard Roman numerals go up to 3999 (MMMCMXCIX). Numbers 4000 and above require either a vinculum (horizontal bar over a letter to multiply it by 1000) or non-standard extensions. Most practical use cases fall well within the 1–3999 range.
Why don’t Roman numerals have a zero?
The Roman numeral system was additive and designed for counting physical objects. Ancient Romans used the Latin word “nulla” (nothing) for the concept of zero, but zero as a numeral wasn’t incorporated because the positional number system wasn’t used in Roman arithmetic. The concept of zero as a mathematical placeholder was developed in India and arrived in Europe via Arabic numerals.
What is MMXXVI in regular numbers?
MMXXVI = 2026. Breaking it down: MM (2000) + XX (20) + VI (6) = 2026.
Are lowercase roman numerals valid?
Yes. iv, ix, xii are equivalent to their uppercase counterparts. Our tool accepts both uppercase and lowercase input. Lowercase is commonly used in document formatting for page numbering in prefaces, introductions, and appendices.
What’s the rule about repeating symbols?
A symbol may be repeated at most three consecutive times. III = 3, but IIII is not standard — you use IV instead. MMM = 3000 is valid, but you cannot write MMMM for 4000 in standard notation.
Where are Roman numerals used today?
Roman numerals are still actively used in: copyright years on movies and TV shows, Super Bowl and Olympic Games numbering, clock and watch faces, book chapter and section numbering, names of monarchs and popes (Queen Elizabeth II, Pope John Paul II), legal document outlines (Article I, Section IV), and architectural inscriptions.
