Roman notation explained

Understand the canonical profile before converting

Learn the supported range, six subtractive pairs and the difference between a readable value and its canonical modern spelling.

Canonical profile6 min read

Canonical Roman numerals from 1 to 3,999

See the symbols, supported interval and explicit exclusions used by a modern canonical Roman numeral converter.

Subtractive pairs6 min read

Learn why only IV, IX, XL, XC, CD and CM are used as subtractive components in the selected modern profile.

Validation6 min read

Separate invalid characters, out-of-range values and readable but noncanonical spellings with deterministic feedback.