Is there anyway I can have two instances of native Calculator app running simultaneously.

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    I'm wondering why you'd want two instances of Calculator. I set Calculator to RPN mode, this gives you a stack that can store intermediate results. – Hobbes May 16 '18 at 19:31
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    The calculator app in Windows 10 will open as many instances as you like.. – trognanders May 17 '18 at 7:57
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    @Hobbes I'm wondering why you would think someone wouldn't want to be able to run two instances of Calculator... maybe they want to do two different calculations at the same time (for some reason) without writing down their intermediate answers. – user253751 May 18 '18 at 4:20
  • In RPN mode your intermediate results remain visible if you want. No need to have a second window open. igor.io/2013/12/02/stack-machines-rpn.html – Hobbes May 18 '18 at 7:10
  • Also, I was asking for a use case because that would enable a better recommendation. – Hobbes May 18 '18 at 7:27

The quickest, simplest and arguably most correct way of doing this is using the open command in Terminal.

In a new window, run the command

open -na Calculator

This will open a new (-n) instance of the application (-a) Calculator.

If you want to have this handy at the click of a button, you can type the following commands into the Terminal, and it will create a shortcut named calc or calc.command on your desktop that will always open a new instance of Calculator

cd ~/Desktop
echo open -na Calculator > calc.command
chmod +x calc.command

Mind that you don't already have a file named calc.command on your desktop, or it'll be deleted!

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    How does open work ? It checks for whatever is in the Applications folder ? – Gabriel Romon May 15 '18 at 20:09
  • @GabrielRomon see the man page here. I don't see it saying explicitly anywhere, but it looks like it's either checking /Applications or using LaunchServices to find it. – scohe001 May 15 '18 at 21:10
  • @GabrielRomon There is a metadata database that tracks stuff like applications; it includes applications found in /Applications and sub-directories, ~/Applications and sub-directories, and even places like /System/Library/CoreServices. – Williham Totland May 15 '18 at 21:10
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    A way that I find helps me "understand" the "open" command is to consider it a direct synonym for the "start" command under Windows. Many many many years ago, that was described to me as "Do whatever is the appropriate thing to make sense of the opened (started) object." So in the case of an app, it'll open it, in the case of a document it'll open it in the associated application, in the case of a url it'll open it in a new browser tab, etc. – dgnuff May 16 '18 at 3:21
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    @dgnuff Another easy way of looking at it is that open is roughly equivalent to a double-click. – Williham Totland May 16 '18 at 13:50

The open -na Calculator answer is good. When I needed to do this before, I wrapped it in an Applescript:

 do shell script "open -n " & quoted form of the POSIX path of the (path to the frontmost application as Unicode text)

This detects which application is currently in the foreground and starts a new instance using the open -na method.

Save this script in the Applescript Editor as something like "Run another instance" and put it in your /Users/${USER}/Library/Scripts directory. You will then find it under the User Scripts Menu (which you may need to enable):

enter image description here

Simply bring the calculator to the foreground, then select this menu item and you'll get another calculator instance.

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    In my opinion, this is by far the best answer, as it is the most general. I.E. do this one thing once, and now you can run multiple instances of any app, not just the Calculator. – Glen Yates May 16 '18 at 16:08

You can run as many as you like and even without duplicates of the application.

Double click the application to open one instance, e.g.


Then double click the executable to open a second instance
(you will have to ctrl+click or right-click the application and select "Show Package Contents" to navigate to the executable):


In this second instance a Terminal window will open to run the executable. Don't terminate it, or you will terminate the second instance of Calculator running.

Double clicking the executable lets you open as many instances of Calculator as you like (meaning I don't know the upper limit).

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    You can also run "/Applications/Calculator.app/Contents/MacOS/Calculator" & from terminal as many times as you want and then close the terminal window. – Scottmeup May 15 '18 at 18:24
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    Yes, that avoids navigating to the executable in Finder, but I still need the window open, or all instances will be terminated. – Redarm May 15 '18 at 18:33
  • Right you are! It seems my recollection was a bit off. – Scottmeup May 16 '18 at 7:33

Yes, you can, if you have an administrator account. Select Calculator.app in Applications, then right-click (control-click) and execute the Duplicate command. This will make a copy of the Calculator app which you can then use freely.

enter image description here

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    This will not make an application run twice but will create a copy of the application and then run the copy – Matteo May 16 '18 at 16:17
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    @Matteo - Yes, correct, but what's the problem here? The OP requested "How can I get two calculators going?" and it does just that. – IconDaemon May 16 '18 at 18:01
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    It works but it’s a waste of space. To execute an application twice you don’t need the same information on the disk twice. – Matteo May 16 '18 at 19:09
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    @Matteo - I still don't see how your comment adds to my post. You're merely stating facts gleaned from other answers. Nothing is wrong with my answer in the least. There may be more elegant ways of running Calculator multiple times, but it works. In any case, 11.7MB of disk space for 2 copies of Calculator is minimal compared with the size of, say, Pages (508MB), Keynote (728MB), Excel (1.75GB!), or even Final Cut Pro (3.76GB.) – IconDaemon May 16 '18 at 19:25
  • There are potentially other problems, like when the original gets updated. @Matteo What about a symlink? This would save space and be automatically updated. – Sparhawk May 18 '18 at 5:43

Open your terminal and run:

open -n /Applications/Calculator.app


open -na Calculator

No need for app copying or anything like that!

From the help options for open:

-n, --new         Open a new instance of the application even if one is already running.
-a                Opens with the specified application.

You can copy the calculator app to a different folder or desktop. Now change the name to something different like Calc ( very original I know). You can now run both.


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