BrownDwarf Converter is free iOS app for iPhone and iPad, first developed by Jonathan Gagné, from University of Montréal

The BD Converter is aimed for astrophysics researchers and students in the field of brown dwarfs. It follows tabulated data from BT-SETTL brown dwarfs atmosphere models to convert a given age combined with any of effective temperature, mass or spectral type, to several other quantities, including the aforementioned as well as surface gravity, radius and standard J, H, K, W1, W2, W3 near-infrared magnitudes from the 2MASS and WISE surveys.

Jonathan has been kind enough to entrust his app to me, at onekilopars.ec, for maintenance and future development.  Hence the BD Converter is now entirely part of the onekilopars.ec portfolio, but credits remain to Jonathan for building this very handy app. 

Image Credits: E.S.O.