Kalkulator is a powerful yet simple to use calculator and numerical Swiss army knife for Windows (from 95 to Windows 8), with features making it especially suitable for scientific and engineering users, including students of these disciplines.

Anyone with some knowledge of programming can write a calculator program and call it "ultimate" or "professional". And, sadly, almost everyone does that, with results ranging from mediocre to pathetic, but still accompanied with all inflated claims of being "greatest", "most powerful" and whatever.

Incidentally, Kalkulator received a 5-star (highest) rating from the ZDNet Software Library, as well as a 4-star (highest, again) rating from the PCWin Resource Center — but don't let any reviewer's opinion affect your choice. Your needs and taste may be different, and not all software reviewers have to be wizards of numerical analysis. Besides, I've seen a number of 5-star programs which were just embarrassing. No names, please...

(If you think Kalkulator is an overkill for your needs, there is a smaller and simpler alternative: check out the Midget sci/eng calculator — you may like it!)

Under Windows Vista, 7, and 8, Kalkulator may experience a problem when trying to save its configuration to disk: Windows (in its default, idiot-proof setup) does not allow an application to create or modify any files inside its own folder if it is nested inside Program Files or Program Files (x86). This limitation can be lifted by changing Windows settings, or Kalkulator can be simply installed elsewhere.

Note: Kalkulator registration keys are not currently available until further notice. If you used PayPal to procure a registration, please cancel the payment. When the full functionality is again available, a notification will be posted here.