Is my input uploaded?

No. The conversion is plain table lookup + integer arithmetic in your browser; nothing is sent anywhere.

Why is the range capped at 3999?

Standard Roman numerals using just `I / V / X / L / C / D / M` only represent 1–3999. Larger values traditionally use a vinculum (overline = ×1000) which is awkward to encode in Unicode, so we stick to the canonical range.

What does "canonical form" mean?

Some values have multiple Roman spellings. For example 4 is canonically IV but watch dials often show IIII. We only accept the subtractive form (IV / IX / XL / XC / CD / CM) and reject non-canonical spellings like IIII.

Is lower case (mmxxvi) accepted?

Yes. Input is case-insensitive; the parser uppercases it internally. Output is always upper-case.

Can I convert 0 or a negative number?

No. Roman numerals have no representation for zero or negatives, so the tool only accepts positive integers from 1 onwards.

Back to Convert

Roman Numerals Converter

Convert between Arabic numbers (1–3999) and Roman numerals (I / V / X / L / C / D / M). Covers the standard range used for year labels, chapter numbers, watch dials, and sequel titles. Runs entirely in your browser — no uploads.

conversioncalculator

How to use

Pick a direction ("Arabic → Roman" or "Roman → Arabic"), enter a value, and hit Run. Arabic input accepts integers 1–3999; Roman input accepts the canonical form using `I / V / X / L / C / D / M`. Lower-case is accepted but output is always upper-case. Everything runs in your browser — no uploads.

FAQ

Is my input uploaded?: No. The conversion is plain table lookup + integer arithmetic in your browser; nothing is sent anywhere.
Why is the range capped at 3999?: Standard Roman numerals using just `I / V / X / L / C / D / M` only represent 1–3999. Larger values traditionally use a vinculum (overline = ×1000) which is awkward to encode in Unicode, so we stick to the canonical range.
What does "canonical form" mean?: Some values have multiple Roman spellings. For example 4 is canonically IV but watch dials often show IIII. We only accept the subtractive form (IV / IX / XL / XC / CD / CM) and reject non-canonical spellings like IIII.
Is lower case (mmxxvi) accepted?: Yes. Input is case-insensitive; the parser uppercases it internally. Output is always upper-case.
Can I convert 0 or a negative number?: No. Roman numerals have no representation for zero or negatives, so the tool only accepts positive integers from 1 onwards.

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