The Windows Calculator does not increase its font size or appearance based on the screen resolution of the monitor your computer is connected to.
It will always display the characters in an eight pixel font size which displays them ridiculously small if your use a large screen resolution.
Microsoft does not offer a way to change the display of the Windows Calculator or adjust the font size automatically depending on the screen resolution of the computer which means that we, once again, have to rely on third party tools to change a default Windows application so that we can work with it.
You do need a software called Resource Hacker for this, the link is at the end of this article. Unpack Resource Hacker and start ResHacker.exe. Now click on File > Open and browse to C:WindowsSystem32 and open calc.exe.
Now browse to the entry 101 and click on the child 1033 (1033 can be another value on your computer, it should display only one entry, click on that). You see many lines of code on the right window including the one important for us: FONT 8, “MS Shell Dlg”
You increase the font size by simply changing the 8 to another number. My suggestion would be to change it to 10 or 12. Click on Compile Script afterwards and you should see the changes immediately in the preview window.
Do the same for the entry 102, 1033. One changes the font size of the scientific calculator while the other changes the font size of the normal calculator.
Before:
After:
As you can see this makes a huge difference. Now save the new calculator using the Save As dialog, name it calc1.exe for instance. Please note that you can’t replace the original calculator from within the software because it is system protected.
The best option in my experience would be to change the shortcut in the start menu to point to the new calculator. Just right-click the shortcut, select properties and change the path under Target accordingly. If you saved it as calc1.exe for instance which was saved to system32 you simply add the char 1 to the path.
I have not found a way to replace the system calculator with the newly created one. If anyone has experience in that matter contact me please.
Still, the change that you make is permanent so that you only need to make it once before the new font size becomes available in the newly saved calculator file.