Roman numerals converter
Convert between Arabic numbers and Roman numerals.
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Tool guide
Roman numerals converter: how it works
Practical information to understand the result and use this tool correctly.
About Roman numerals converter
Classical Roman numerals use I, V, X, L, C, D, and M. Subtractive pairs like IV (4) and CM (900) keep strings shorter.
This converter covers 1 through 3999, the usual range for clocks, outlines, and historical dates without overline notation.
Unicode “Roman” characters in some fonts are different symbols—this tool uses plain ASCII letters I–M.
How to use it
- 1Enter an Arabic number or a Roman string.
- 2Choose mode (to Roman or to Arabic).
- 3Read the conversion result.
Frequently asked questions
- Why stop at 3999?
- Larger values traditionally need overlines or other marks not standardized in plain text.
- Is IIII valid for 4?
- Clocks sometimes use IIII, but standard written form is IV. This tool follows the standard subtractive form.