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What is GlassCalc?

GlassCalc is a free, Windows calculator designed for quick input via keyboard. It forgoes the usual array of buttons for a single textbox where you can type an equation or mathematical expression, hit Enter, and get a result.

Physical calculators have buttons for a reason—you can press those buttons with your fingers. However, unless you have a touchscreen or tablet, having the same buttons on a software calculator makes little sense. You can’t press those buttons with your fingers; you have to use your mouse. Besides, computers already have physical buttons, (we call that the keyboard) so why not use them?

The name, “GlassCalc”, comes from the extra bit of Aero glass and my total inability to come up with anything else. I started making GlassCalc when I discovered that the Microsoft PowerToy Calculator didn’t work properly in Windows Vista/7 without administrative privileges. I wanted a calculator that I could quickly type equations into without getting a UAC prompt every time I started it.


What’s It Do?

GlassCalc is an all-purpose calculator. It keeps a full history of past equations (calculator tape), shows reference listing of all available functions, and lets you define your own constants, variables and functions. It supports evaluating multiple expressions at once, and unit conversions with GNU Units.

GlassCalc uses Mathieu Jacques’ MTParser and a bunch of regex magic to parse and evaluate equations. It is capable of (but not limited to) the following:

  • Evaluating all kinds of simple and complex mathematical expressions.
  • Evaluating multiple expressions at once.
  • Handling user-defined functions and variables.
  • Keeping a full history of expressions and results. (calculator tape)
  • Remembering all your variables and functions (and if you choose, the history as well) when the program is closed and restarted.
  • Converting to and from any base between 2 to 36. There are shortcuts for entering binary, octal, and hexadecimal numbers as well.
  • Solving single variable equations. (except in the cases where Newton’s Method fails or limited precision causes problems)
  • Evaluating trigonometric functions with either radian or degree angles.

Click Quick Reference under the Help menu for a concise listing of the functions available in GlassCalc, or look at the readme for more in-depth descriptions.

GlassCalc also features a number of shortcuts designed to make it quick and easy to make calculations. For instance, simply start typing and the input textbox will automatically receive focus—no need to click it first. GlassCalc also recognizes coefficients (so 3x and 3*x both mean “3 times x”), and exponential notation (so 1.2e4 means “12 times 10^4”).

System Requirements

  • Microsoft Windows XP, Vista, or 7 (untested on older versions)
  • .NET Framework 4.0 (automatically installed during setup if needed)

If a previous version of GlassCalc worked on your computer, click the upgrade button below for a much smaller download.


GlassCalc supports unit conversions if you have GNU Units installed. See my post on GlassCalc 1.24 for more details.

You can add extra constants or overwrite the default ones. See my post on GlassCalc 1.25 for more details.

You can define suffixes to automatically scale numbers so that, for instance, 1K means 1000. See my post on GlassCalc 1.28 for more details.

Please tell me what you think!

There isn’t a comments section on this page, but I’ve set up a place where you can give suggestions, complain about bugs, or just tell me that you use GlassCalc. I know people are downloading GlassCalc, (because Google Analytics says so) so I’d really like some feedback so I can make it even better! Here’s the comments page.

Download GlassCalc Upgrade to version 1.35