Roman Numeral Converter
Convert standard Roman numerals and integers from 1 to 3999
Conversion results
Enter a value and select Convert to see results here.
Spelling and range
The subtraction pairs are IV, IX, XL, XC, CD and CM. Write 49 as XLIX; IL, IIII, VX and MMMM are rejected. Historical variants such as clock-face IIII are outside this tool’s scope.
Decimal input must be an integer from 1 to 3999; leading zeros are accepted (0049 → XLIX). Zero, negative numbers, fractions, exponents, thousands separators, internal spaces and Unicode numeral symbols such as Ⅳ are unsupported.
The full guide also includes pitfalls, worked examples, snippets, FAQs, and related tools for checking results or troubleshooting.
About this tool
Convert a decimal integer from 1 to 3999 to standard Roman numerals, or convert a standard Roman numeral back to decimal. Both directions return decimal, uppercase and lowercase Roman, binary and hexadecimal values. Enter 49 or XLIX to get 49, XLIX, xlix, 110001 and 0x31. Lowercase input and surrounding whitespace are accepted; decimal leading zeros are removed. Conversion is explicit, and editing clears the previous result. Input is processed locally and is not saved to browser storage or sent to analytics.
Scenario Recipes
Read a year written in Roman numerals
Goal: Convert MCMXCIV into a decimal year without guessing subtraction pairs.
- Enter MCMXCIV (lowercase mcmxciv is also accepted).
- Select Convert. The decimal result is 1994.
- Check the parts: M = 1000, CM = 900, XC = 90 and IV = 4. Copy the Decimal result.
Result: MCMXCIV becomes 1994. This converts the number; it does not infer a date, calendar era or historical meaning.
Production Snippets
Check 49 in both directions
text
Input: 49 or XLIX
Decimal: 49
Standard Roman: XLIX
Lowercase Roman: xlix
Binary: 110001
Hexadecimal: 0x31Frequently Asked Questions
Why are IL and IIII rejected?
This tool accepts standard subtractive notation only: 49 is XLIX and 4 is IV. Additive clock-face IIII and other historical variants are outside its scope; invalid forms are not silently repaired.
What is the supported range?
Both directions are limited to 1–3999. Zero, negative values, fractions and overline notation for larger numbers are unsupported. The largest accepted Roman value is MMMCMXCIX (3999).
Can I enter lowercase letters or leading zeros?
Yes. For example, xlix and 0049 both produce decimal 49 and standard Roman XLIX. Surrounding whitespace is trimmed. Internal spaces and Unicode numeral symbols such as Ⅳ are not accepted.
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