GKalk is a free-form calculator for Mac OS X and Windows. Compared with other calculator-type applications, GKalk has two main features that distinguish it from them:

  1. GKalk uses the GNU Multi-Precision Arithmetic Library to provide integers with virtually unlimited digits. For example, using GKalk you can evaluate 2 to the power of 1.000.000, which is a number with more than 300.000 digits. In a way, you can think of GKalk as a very easy-to-use frontend to the GMP.
    GKalk also uses the GNU MPFR Library to provide decimals with much higher precision that most builtin floating point numbers.
  2. GKalk allows you to type multiple expressions in multiple lines - and evaluates them instantly, as you go along. This allowes you to see both the expressions and the results at a single glance.

Why should I care?

As an regular visitor of this website you may ask why is this in any way different from pcalc, pcalc.net, or gcalc, all tools I've written in previous incarnations -: There are four answers, each equally impressive:

  1. Because I say so, period.
  2. Because the name GKalk is totally different from pcalc, pcalc.net, or gcalc.
  3. Because it was my very first full-fledged program for Mac OS X, and by now my very first program in the Mac OS X App Store. But it is not available there any more because I didn't want to renew my license. GKalk is freeware, and Apple charges you to release Freeware, which I don't fully understand. But that is just because I am too old to get these things!
  4. Because the newly rewritten engine uses GMP and MPFR, but you KNOW that already, don't you.

How does it look like on a Mac?

The Windows GUI has been completely revamped for version 4.0, and it is by now pretty sophisticated:

The screenshot should be pretty instructive on how this works, right?

GKalk has a very minimalist GUI on Mac OS X:

How do I use it?

You type a mathematical expression, like 4+3*2, or sin(pi)*cos(pi). GKalk evaluates the expression as you type, showing you results immediately. If you are familiar with math, things couldn't very well get much easier than that... :)

You can also use GKalk to define your own variables, like this:a=1860, and then continue to refer to a whenever you want that particular number. You can even define your own functions (within limits), like this:f(x)=sin(x)*sin(x)+cos(x)*cos(x)

For more information, refer to the following additional sections

Also, check out the future plans for GKalk.

What GKalk is not

GKalk is not an system for algebraic number manipulation. GKalk is not R. GKalk is rather disappointing at making coffee. I am sorry for the inconvenience caused.



GKalk is freeware, BSD-licensed. Obviously, I will forfeit my chance of ever getting stupid rich by giving this brilliant thing away for free, but so be it.

Note: GKalk uses the FamFamFam.com Silk icon set - check it out, it's great!


GK, Feb 16, 2014