The newest entry into the crowded field of conversion utilities is from the developers at Tapbots. That alone is worthy of our attention and Convertbot does not disappoint.

PCalc RPN Calculator has an optional RPN mode and a plethora of conversions built-in, a two-line display, undo and redo, and just about everything else one would expect from a scientific or engineering calculator. Its display is fully customizable and includes themes, various color options, landscape/portrait mode, and more. It’s an expensive calculator but it has an exhaustive set of features.

A well done conversion utility priced right in a very crowded category.

Number conversion utility with great options.