Free Roman Numeral Converter: Arabic to Roman & Back
ℹ️ Vinculum notation: For numbers above 3,999, a line above the letter is used, which multiplies the value by 1000×
Example: V = 5,000 | X = 10,000 | M = 1,000,000
Use the format _V_ for input (for example _X_ = 10,000)
Examples
Are you planning a birth date tattoo, deciphering a year on a historical building, or just curious how to write the current year in Roman numerals? Our advanced converter handles it instantly – in both directions.
We support not only the classic numbers you know from school (I, V, X, L, C, D, M) but are also one of the few that can handle large numbers above 3,999 using the Vinculum notation (a line above the letter). Everything works online, for free, and without installation.
Why is our converter unique?
Most online calculators stop at 3,999 (MMMCMXCIX). We go further – up to millions.
- Two-way conversion: Enter “2024” and get “MMXXIV”, or type “MCMLXXXIX” and find out it’s the year 1989.
- Support for large numbers (Vinculum): Need to convert 10,000 or a million? Our algorithm automatically uses the historically accurate notation with a horizontal bar, which multiplies the value by a thousand.
- Smart input: Don’t have a character with a bar on your keyboard? No problem. Our tool accepts special notation (e.g.,
_V) to make working with Roman numerals easy, even on a computer.
Comprehensive Overview: Roman Numeral Table
The Roman system has no zero and is based on addition and subtraction. Here are the basic building blocks of the system and special characters for large numbers that our widget supports.
| Roman Character | Arabic Value | Note |
|---|---|---|
| I | 1 | Basic unit. |
| V | 5 | Five. |
| X | 10 | Ten. |
| L | 50 | Fifty. |
| C | 100 | Centum (hundred). |
| D | 500 | Five hundred. |
| M | 1,000 | Mille (thousand). Common limit of old systems. |
| V | 5,000 | V with a bar above (5 × 1000). |
| X | 10,000 | X with a bar above (10 × 1000). |
| C | 100,000 | C with a bar above. |
| M | 1,000,000 | Million. |
Instructions: How to Enter Large Numbers and Dates
The operation is simple, but for advanced functions (numbers above 4000), we offer some clever features.
1. Arabic -> Roman Conversion
In the left field, type any number (e.g., 2024 or 123456).
- The result will instantly appear on the right.
- For very large numbers, the Vinculum notation (a line above the letters) will be automatically used, which you will see in the large preview below the fields.
2. Roman -> Arabic Conversion
In the right field, type Roman characters (I, V, X…).
- How to type a character with a bar? If you want to write the number 5,000 ($\overline{\text{V}}$), use the format with an underscore before the letter:
_V. - For example, for 10,000, type
_X. Our system will understand this and convert it to the number 10,000.
3. Example Buttons
Below the widget, you’ll find buttons with popular numbers (e.g., the current year or a million) that will show you what the correct notation looks like.
System Logic: When to Add and When to Subtract?
Roman numerals can be tricky. Why is 4 written as IV and not IIII?
- Addition: If a smaller number is after a larger one, it is added.
- Example: VI (5 + 1 = 6), MC (1000 + 100 = 1100).
- Subtraction: If a smaller number is before a larger one, it is subtracted.
- Example: IV (5 - 1 = 4), CM (1000 - 100 = 900).
- Repetition Rule: No character should be repeated more than 3 times in a row (which is why 40 is not XXXX, but XL). Our converter strictly adheres to these rules.