Windows Calculator, Mathematica, Wolfram Alpha, Google Calculator, SpeedCrunch, fxSolver, Cymath, Simple Calculator, Qalculate!, TextPipe, GeoGebra Scientific Calculator, Text Mechanic, GNOME Calculator, Manipulist, Textslave, Converters360, Word-Counter, Calistry.org, Mefancy, Counting Characters are some alternatives to ThinkCalculator.