There are plenty of reasons to free up storage space, whether you need to download or install new applications or if you’re suffering from performance issues associated with a full storage drive. Our guide will help you work out what approach might work best for you.
When your hard disk drive or solid state drive is getting full, you’ll notice that program performance and overall computer responsiveness will slow down. The drive needs about 20% of its space to find existing information and write new information. You might also notice that you aren’t able to install new applications because of space limitations.
First, check your storage drive to see how much space is available.
Or
In either case, the total capacity of the drive and the remaining capacity will be listed.

You can do a few things to free up space on your storage drive. The biggest thing is to go through your files and applications to delete or move to an external storage drive or the cloud items you no longer want.
To look at a list of your applications, and their size, follow these instructions:
Starting with the largest files, delete any that you don’t use anymore. Additionally, you can filter files by Last Used to get a quick view of old files you might want to clear out.
Clean out the Downloads file by clicking on the drive icon on your desktop, select your user name, then find the Downloads file. Delete any items that have been saved somewhere else or that you no longer need.

Go into Mail and delete attachments from your emails that you don’t need or that have been saved. In Mail, select View, then Sort by, and Attachments. This will move the emails that have attachments to the top of the list. Open all your Document files to see if there’s anything you can delete.
If you switched from iPhoto® to Photos, you might have duplicate libraries; one in each application. Open each application and compare the photos to see if you can delete one set of pictures.
Go through your photos to see if there are any you want to keep but don’t need access to all the time. These can be moved to an external drive or the cloud.
After you’ve gone through all your applications and files to free up space, be sure to empty your trash cans. Items in the trash cans are still taking up space on your drive. Right-click on the trash icon and select Empty Trash. iPhoto, iMovie, and Mail all have their own trash. Right-click on Trash in each program and select Empty Trash.

If you have OS X® Sierra or beyond, there is a feature that allows you to specify your storage options. To find these options, click the Apple menu then About this Mac, select Manage, then Storage Tools. There are four options: