Roman Numeral Converter
Convert decimal integers and standard Roman numerals in either direction. The supported range is 1–3999; noncanonical combinations are rejected.
Key features
- Detect the direction automatically or select it explicitly.
- Validate canonical subtractive forms such as IV, IX, and CM.
- Convert multiple values in order, one per line.
How to use
- Enter one integer or Roman numeral per line.
- Choose automatic detection or a conversion direction.
- Run and review the output; correct any invalid notation reported.
Use cases
- Read chapter numbering
- Write a commemorative year
- Check Roman numeral exercises
Frequently asked questions
What range is supported?
Integers from 1 through 3999. Zero, negative numbers, fractions, and overline notation for larger numbers are not supported.
Are IIII and IC accepted?
No. Use canonical forms such as IV and XCIX. Additive IIII used on some clocks is outside this tool’s notation.
Can I use lowercase letters?
Yes. Lowercase input such as iv is accepted, and generated numerals are uppercase. Enter Latin letters IV rather than the single Unicode symbol Ⅳ.
Are leading zeroes accepted?
No. Use ordinary decimal integers from 1 to 3999. Surrounding whitespace on a value is ignored, while blank lines are preserved.
Privacy
Input and results are processed in your browser. This tool does not send or save their contents to a server. Shared site advertising, visitor analytics, and aggregate tool-use measurement may operate separately.
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