RTM_TimerCalc V1.3 is an Advanced Arduino Timer Calculator. Its standard Help page has not caught up to latest changes and extras.
But, there's additional info you can check out that should help you get better acquainted.
For starters, there's the Release Notes that describes new InPin capabilities. It also hints at the ability to quickly convert Units from one type to another (Hz, uSec, mSec, Second, Minute, Hour). You'll find Boundary-Reports covered along with numerous points regarding Calculation Report readouts. A new Limits-Report is covered too.
Another Document describes changes to V1.3 relative to previous versions. There's plenty in there along with details on the new Limits-Report and some hidden features you may find useful.