I want to replace the default Windows 10 calculator with CalcTape.exe in the registry. How and where would I find this in the Windows 10 registry editor? :-)

  • To my knowledge, there is not a program or button that will launch the windows calculator, so setting your shortcuts right should be all you need to do. Occasionally there are keyboards that have a calculator button, these often just call calc.exe. If you rename calctape.exe to calc.exe and set it first in your path environmental setting, it should work there too.
    – LPChip
    Jan 13, 2019 at 17:18
  • @LPChip - Microsoft used to sell Keyboards that would launch specific programs, but Windows 10 only has the UWP calculator application, so renaming the executable isn’t a viable solution
    – Ramhound
    Jan 13, 2019 at 17:33
  • 1
    I have a Logitech keyboard with a calculator button, FWIW (key name XF86Calculator according to what I've bound in Openbox)
    – bertieb
    Jan 13, 2019 at 18:06

3 Answers 3


One method that isn't too invasive and can easily be undone is to use the Image File Execution Options Debugger key. This is the same method employed by Process Explorer when you replace Task Manager.

If you typically run calc or calc.exe to launch the Calculator this will work:

  1. Launch Regedit
  2. Navigate to : HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options
  3. Create a new reg key called calc.exe under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options.
  4. Create a new string value called Debugger.
  5. The data value can then be the path to your custom exe.

A reg file export of such an update would look like the following if this is simpler to follow:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image
File Execution Options\Calc.exe]     

This will work for the above scenario but then there are a number of ways to launch an application and this will not cover all of them.

  • super cool tips... any chance you know how to set default app for maps? especially for point 3 and 4 Aug 21, 2022 at 3:04

The top answer will change the app that's launched with the calc command, but the calculator key may still need further configuration:

To change the app that's launched when you press the calculator key, change the following registry value:


Set ShellExecute to the path you want, for example: C:\Program Files\CalcTape.exe.

Alternatively, you can set up a macro: AutoHotkey: how to assign a command to the "Calc" key?

  • This is the most elegant solution (or at least as far as it can get with Windows and registry)... Feb 1 at 17:02

I did it by renaming calc.exe to ms calc.exe Then I copied my chosing calculator moffFreeCalc.exe as calc.exe and copied that to windows\system32

Had to take ownership of the ms calc file first, before beimg able to rename it.

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