Roman Numerals Converter
Convert between Roman numerals and decimal numbers with ease
Decimal to Roman Numerals
Roman Numerals to Decimal
Table of Contents
How to Convert Roman Numerals
Our calculator provides two-way conversion between Roman numerals and decimal numbers:
- Decimal to Roman: Enter any number between 1 and 3999
- Roman to Decimal: Enter valid Roman numerals using I, V, X, L, C, D, and M
- Case-insensitive input for Roman numerals
- Instant conversion with validation
Roman Numeral Rules
Basic Roman numeral symbols and their values:
- I = 1
- V = 5
- X = 10
- L = 50
- C = 100
- D = 500
- M = 1000
Key rules for Roman numerals:
- Numbers are generally written largest to smallest, left to right
- When a smaller value precedes a larger value, subtract the smaller from the larger
- Only I, X, and C can be used as subtractive numerals
- A symbol cannot be repeated more than three times in succession
Common Uses and Applications
- Historical dates and inscriptions
- Book chapter numbering
- Clock faces and watches
- Movie and TV show copyright dates
- Educational purposes
- Formal documents and legal numbering
Tips and Tricks
- Learn common patterns (e.g., IV = 4, IX = 9, XL = 40, XC = 90)
- Remember that subtractive notation is used for numbers like 4, 9, 40, 90, etc.
- Practice with years and dates to become familiar with larger numbers
- Use the calculator to verify your manual conversions
Frequently Asked Questions
Why can't I convert numbers larger than 3999?
Traditional Roman numerals only go up to 3999 (MMMCMXCIX). Numbers larger than this require special notation that isn't universally standardized.
Are Roman numerals still used today?
Yes, Roman numerals are still used in various contexts, including clock faces, book chapters, movie copyright dates, and formal documents.
What is subtractive notation?
Subtractive notation is when a smaller numeral is placed before a larger one, indicating that the smaller value should be subtracted. For example, IV represents 4 (5 - 1).