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

  • 1
    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, 2018 at 19:31
  • 1
    The calculator app in Windows 10 will open as many instances as you like.. May 17, 2018 at 7:57
  • 4
    @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, 2018 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, 2018 at 7:10
  • 1
    Also, I was asking for a use case because that would enable a better recommendation.
    – Hobbes
    May 18, 2018 at 7:27

7 Answers 7


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!

  • 1
    How does open work ? It checks for whatever is in the Applications folder ? May 15, 2018 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, 2018 at 21:10
  • 3
    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, 2018 at 3:21
  • 6
    @dgnuff Another easy way of looking at it is that open is roughly equivalent to a double-click. May 16, 2018 at 13:50
  • 2
    Just pointing out how absurd the Mac is for forcing someone to open a terminal and type cryptic text in to just spawn another instance of the most basic tool a computer has.
    – LMS5400
    Sep 28, 2021 at 17:47

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.

  • 3
    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, 2018 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).

  • 1
    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, 2018 at 18:24
  • 1
    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, 2018 at 18:33
  • Right you are! It seems my recollection was a bit off.
    – Scottmeup
    May 16, 2018 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

  • 2
    This will not make an application run twice but will create a copy of the application and then run the copy
    – Matteo
    May 16, 2018 at 16:17
  • 4
    @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, 2018 at 18:01
  • 7
    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, 2018 at 19:09
  • 1
    @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, 2018 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, 2018 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.


If you are unable to change sharing permissions on the Calculator.app file and make a copy using the Duplicate option, then this way should work for you.

  • Open the Shortcuts app that comes with macOS.
  • Create a new shortcut with the plus sign.
  • In the 'Search for apps and actions' field at top right type the word "run"
  • Now drag the 'Run Shell Script' option from the right pane into the main pane for your action. (Note: You may be prompted to allow running scripts).
  • Replace the default echo "Hello World" script text with: open -n /System/Applications/Calculator.app.
  • Rename your shortcut from "Run Shell Script" to something more meaningful (remembering to press return) and then close the window.
  • Go back to the main Shortcuts window and drag your newly created shortcut from the "All Shortcuts" main pane to the "Menu Bar" folder in the right pane.
  • You should now be able to access the shortcut in your top menu bar and create multiple instances with it.

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