Links

Compvter Romanvs

An actual, working Roman numeral calculator. (Requires a Java-compatible browser.) It also has explanations of Roman numeral syntax, conversion, and the Roman calendar.

Roman Numeral and Date Conversion with Roman Calculator & Roman Numerals Test

It's a mouthful, but that's pretty much what's on this site. It's all written in JavaScript, so you'll have to have a JavaScript-enabled browser and have JavaScript turned on to use the converters here.

Roman Numeral Date Conversion Guide

This explains everything you wanted to know about reading years written in Roman numerals, including alternative forms and the apostrophus. Much more in depth than anything you'll find here.

Roman Numerals and Dates

Discusses converting dates into Roman form and the history of Roman numerals, plus it has conversion tables.