KoalaCalc is a free multi-purpose calculator for Mac OS X. In its compacted state, it looks similar to the standard calculator that comes with Mac OS X. However, simply click the 'advanced features' box and KoalaCalc comes to life to become one of the most advanced scientific, conversion, statistical and expression calculators available.

The list of features includes:

• Numerous mathematical functions including trig and log functions plus 10 individual memory banks
• Conversion to and from dozens of units (inches to millimeters, pounds to kilograms, etc.)
• Basic statistical calculations on up to 10 data sets including t-tests and analysis of variance (ANOVA)
• Built-in tape recorder (contents can be saved, recalled, or printed)
• Voice feedback (button pressed and/or computed value can be read aloud)
• Built-in expression calculator which supports brackets and the proper order of operations
• Probability calculator computes exact p value based on the F distribution, with or without epsilon correction (this unique feature is useful for statistical calculations)
• Constants menu which can be customized
• No silly 2nd function button - all features have their own button
• Most buttons including advanced scientific functions include keyboard shortcuts - a real time saver
• Help on how to use each button is provided by simply leaving the mouse cursor over a button for a few seconds
• User can set various preferences including
• Advanced features can be hidden to reduce the size of the footprint