Help! 55 GB for Applications in Finder vs. 740 GB shown in 'manage storage' for Applications?

What year model iMac and what macOS version is it running...?

see > Identify your iMac model - Apple Support

Do you have a Time Machine backup drive that has failed or is no longer backing up...?

If so, see > View APFS snapshots in Disk Utility on Mac - Apple Support

Hey there!

First, I'd suggest that you use safe mode on your Mac.

To use safe mode, follow these steps:

If you're using a Mac with Apple silicon

1. Shut down your Mac.

2. Press and hold the power button on your Mac. As you continue to hold the power button, your Mac turns on and loads startup options. When you see Options, release the power button.

3. Select your startup disk. It's named Macintosh HD, unless you changed its name.

4. Press and hold the Shift key, then click the “Continue in Safe Mode” button below your startup disk.

5. Log in to your Mac. You might be asked to log in again.

If you're using an Intel-based Mac

If you're not using a Mac with Apple silicon, you're using an Intel-based Mac.

1. Turn on or restart your Mac, then immediately press and hold the Shift key as your Mac starts up.

2. Release the key when you see the login window, then log in to your Mac. 

3. You might be asked to log in again. On either the first or second login window, you should see ”Safe Boot” in the upper-right corner of the window. If you can't start up in safe mode, make sure that your Mac isn't using a firmware password.

Once in safe mode, go back to storage settings in System Settings > General > Storage. Take note if the issue continues, then leave safe mode by restarting your Mac normally.

If the issue persisted in safe mode, rebuild the Spotlight index on your Mac, which may help correct inconsistencies in storage. This Apple Support article should help: Rebuild the Spotlight index on your Mac - Apple Support.

If you still see the storage calculation issue, take a screenshot of the whole manage storage display, so we can see how your Mac is calculating the total used storage amount.

-Jack