ESBUnitConv provides you with a portable option for numerous types of measurement conversions.
We have it marked Freemium because there is a pro version that you can upgrade to which offers approximately 400+ additional units. But the free version will suffice for most users as it covers 613 Units in 21 different measurement categories.
ESBUnitConv is very user-friendly permitting you to convert between units of measurement easily. It includes Units for Temperature, Distance, Mass, Area, Volume, Pressure, Velocity, Acceleration, Force, Energy, Power, Fuel Consumption, Flow, Torque, Angles, Luminous Intensity, Illumination, Time, Quantity & Radioactivity. It is an older app, but the conversions check out and operation is smooth. Even if you don't upgrade, the free version is fully functional and extremely simple to use.
Limitations:
Pro version is only $19.00 and includes 1025 Units in 38 different measurement categories as well as the following:
Logging of Conversions
Ability to Hide Units
Scaling
American Wire Gauge Table
Circle Calculator
Sphere Calculator
Value Swapping
SI Primary Unit displayed in Bold
SI Primary Unit can be selected quickly via Button
Free42 HP-42S Calculator Simulator is an Open Source recreation of the HP-42S Scientific Programmable Calculator and HP-82240 Printer. Plus42 is also available.