Roman Numeral Converter Roman Numeral Converter Convert between Arabic numbers and Roman numerals, validate your Roman strings, and even convert dates like 2025-11-07 → VII • XI • MMXXV. 1. Number ➜ Roman Enter a number (1–3999) Convert to Roman Roman numeral — 2. Roman ➜ Number Enter a Roman numeral (I–MMMCMXCIX) Convert to Number Arabic number — 3. Date ➜ Roman Useful for inscriptions or fancy headings. We convert day, month, year separately. Select a date Convert date Date in Roman numerals — Roman numeral rules Roman numerals are built from these symbols: Symbol Value Notes I 1 V 5 X 10 L 50 C 100 D 500 M 1000 IV, IX 4, 9 Subtractive notation XL, XC 40, 90 Subtractive notation CD, CM 400, 900 Subtractive notation This tool enforces standard modern form (no overlines, no 5000+, no non-standard repetitions). Related Math & Conversions Number to Words Converter Words to Numbers Converter Measurement Unit Conversions Core Math & Algebra Common conversions 2024 → MMXXIV, 1999 → MCMXCIX, 44 → XLIV If you get “invalid Roman numeral”, check for too many repetitions (e.g. IIII), or illegal subtractive pairs (like IL).

Calculators in Roman Numeral Converter Roman Numeral Converter Convert between Arabic numbers and Roman numerals, validate your Roman strings, and even convert dates like 2025-11-07 → VII • XI • MMXXV. 1. Number ➜ Roman Enter a number (1–3999) Convert to Roman Roman numeral — 2. Roman ➜ Number Enter a Roman numeral (I–MMMCMXCIX) Convert to Number Arabic number — 3. Date ➜ Roman Useful for inscriptions or fancy headings. We convert day, month, year separately. Select a date Convert date Date in Roman numerals — Roman numeral rules Roman numerals are built from these symbols: Symbol Value Notes I 1 V 5 X 10 L 50 C 100 D 500 M 1000 IV, IX 4, 9 Subtractive notation XL, XC 40, 90 Subtractive notation CD, CM 400, 900 Subtractive notation This tool enforces standard modern form (no overlines, no 5000+, no non-standard repetitions). Related Math & Conversions Number to Words Converter Words to Numbers Converter Measurement Unit Conversions Core Math & Algebra Common conversions 2024 → MMXXIV, 1999 → MCMXCIX, 44 → XLIV If you get “invalid Roman numeral”, check for too many repetitions (e.g. IIII), or illegal subtractive pairs (like IL)..