Microsoft Calculator is a calculation application for Microsoft Windows. It was first copyrighted in 1981, when Microsoft's IBM PC-DOS 1.0 was released.

The relatively small sized program (112 kilobytes in Windows XP) is bundled with most versions of Microsoft Windows. By default, it is available by clicking the start button, selecting Programs or All Programs depending on which version of Windows is running, then selecting Accessories, and finally clicking on Calculator. It is alternativly available by selecting Start, Run..., typing calc, and pressing OK.

Calculator, despite its simple interface and small size, can perform all of the functions of most four-function or scientific calculators. By default, the application is in the Standard mode, and functions as a four-function calculator. By selecting View, then Scientific, more advanced functions are available. Most notable is the ability to convert between bases, something that is hard to do by hand.

Reading the help files aids the use of the calculator. To see this file, select Help at the top, and click Help Topics. Due to the popular use of the tool, many multimedia keyboards contain a calculator key for one button access to the cacluator mode. This is usually located at the top of the number pad.