Roman numeral calculator

This tool provides fast, two-way conversions between Roman numerals and Arabic integers, aimed at students, educators, researchers, and developers who encounter inscriptions, historical texts, or data stored in legacy numeral formats. It helps validate input, reduce manual lookups, and improve accuracy when translating numeric values across notation systems. The scope covers standard, subtractive Roman notation up to 3999.

For Roman to Arabic, the system interprets a string of I, V, X, L, C, D, M and sums values while applying subtractive rules (IV = 4, IX = 9, etc.). For Arabic to Roman, it uses a greedy decomposition against thousands, hundreds, tens, and units to produce canonical forms such as MCMXCIX for 1999. The tool emphasizes canonical, unambiguous results to support testing and documentation.

Audience benefits include quick data normalization for educational worksheets, validation during archaeology or history research, and reliable numeral handling in software, databases, and APIs. Unique differentiators include strict canonical validation, explicit diagnostic feedback, and deterministic outputs in a compact, dependency-free implementation environment.