Tool
Roman Numeral Checker
Enter a Roman numeral to see whether it is canonical, what value it implies when safe to infer, and the corrected modern form.
Examples: IV (valid) · IIII → IV · IL → XLIX · ABC (not a Roman numeral)
What “canonical” means here
This checker uses the modern standard rules for 1–3999: valid subtractive pairs only (IV, IX, XL, XC, CD, CM), no repeated V/L/D, and preferred subtractive forms instead of long additive runs like IIII.
Clock dials sometimes use IIII for 4—that dial convention is explained on IIII vs IV and is not treated as the converter’s canonical form.