Roman-Arabic

Roman-Arabic is a simple application that does what its name suggests, providing you with a simple method of converting Roman numerals to Arabic, as well as performing the inverse operation.

Lightweight application that does not need to be installed on your PC

Roman-Arabic is a fully portable program, which means that it can be executed from any location on your computer without being installed beforehand. You even have the option of running it from portable storage devices, and it is not dependent on any third-party software.
You can just unzip the downloaded archive and run the contained executable file or move it to any other folder on your hard drive.

No-nonsense Roman numeral converter

Roman-Arabic is as simple as an application can get. Units are converted as soon as you write a value in each field, so you do not have to waste time clicking any buttons.
The maximum Arabic value is 3999, and the maximum number of Roman numerals that can be inserted is 10.
If you input an invalid number in either of the two fields, a pop-up window is displayed to let you know why it is not supported.

Simplistic interface that takes up a minimal amount of screen space

Naturally, you would expect a basic unit converter to be relatively unobtrusive, and this utility does a good job of staying out of your way. The application window is very small, so you can just place it in one of the corners of your desktop and get on with your other tasks.
However, it would have been great if the program offered you the option of keeping the window on top of all other applications. Additionally, the title bar does not include a Minimize button, which might have come in handy.
Overall, Roman-Arabic is a reliable, easy-to-use application that can help you convert Roman numerals to Arabic and vice versa. It features a minimalistic interface and requires no installation procedure, as it is fully portable.