PS4:Upgrading your Hard Drive

Prerequisites

To upgrade/replace the HDD you will need:

An external USB hard drive or flash drive at least 2GB in size, or large enough to store a backup of all your game saves/applications, if you want to keep them.
A PS4 recovery firmware that matches the same version already installed, or newer. (You can get the latest from playstation.com)
A computer that can connect to the USB drive
A Phillips #1 screwdriver
A 2.5" (laptop size) HDD or SSD large enough to store any content you are migrating from the old drive.

Format the USB drive as FAT32 or exFAT
Connect the USB drive to the PS4
On the PS4, navigate to Settings → System → Backup and Restore → Backup
Choose what content you would like to back up. The process may take hours to complete depending on your selections
Unplug the USB drive from the PS4

Shut down the PS4
Unplug all cables from the PS4
Slide the cover to the side of the console until it pops and you can remove it (the one on the top right with "SONY" written on it right above the disc drive)
Unscrew the HDD retention screw (the screw with PS symbols on it next to the HDD)
Slide the HDD caddy out of the system
Unscrew the four screws holding the hard drive into the caddy
Slide the hard drive out of the caddie
Insert the new HDD in the caddie in the same orientation as the old drive
Install the four screws that hold the HDD to the caddy
Insert the HDD caddie into the console
Install the HDD retention screw
Reassemble the console and reconnect the cables

Shut down the PS4 Slim
Unplug all cables from the PS4 Slim
Slide the HDD bay cover (located on the bottom opposite side of the power plug)
Unscrew the HDD retention screw (the screw with PS symbols on it in the middle of the HDD caddy)
Slide the HDD caddy out of the system
Unscrew the four screws holding the hard drive into the caddy
Slide the hard drive out of the caddie
Insert the new HDD in the caddie in the same orientation as the old drive
Install the four screws that hold the HDD to the caddy
Insert the HDD caddie into the console
Install the HDD retention screw
Reassemble the console and reconnect the cables

Shut down the PS4 Pro
Unplug all cables from the PS4 Pro
Pull up the HDD bay cover (located on the bottom opposite side of the power plug)
Unscrew the HDD retention screw (the screw with PS symbols on it in the middle of the HDD caddy)
Slide the HDD caddy out of the system
Unscrew the four screws holding the hard drive into the caddy
Slide the hard drive out of the caddie
Insert the new HDD in the caddie in the same orientation as the old drive
Install the four screws that hold the HDD to the caddy
Insert the HDD caddie into the console
Install the HDD retention screw
Reassemble the console and reconnect the cables

Plug the cables back in and start the PS4. The console will fail to start up and will ask for a firmware file to install
Download your recovery firmware of choice or the latest from playstation.com
If you didn't format the USB drive in a previous step format the USB drive as FAT32 or exFAT
Create a folder in the root of the USB drive called PS4. Inside that folder create another folder called UPDATE and place the recovery firmware file there named PS4UPDATE.PUP The final path should be <drive root>\PS4\UPDATE\PS4UPDATE.PUP
Plug the USB drive into your PS4 and follow the onscreen instructions to install it
- This will format the new hard drive automatically; it may take some time
Follow the onscreen instructions to set up the system

Connect the USB drive that you used during the backup process
On the PS4 navigate to Settings → System → Backup and Restore → Restore, and select the backup you had made previously. This process may take hours to complete. Your system will be erased and the restore process will begin.
Once complete your profile and any content you chose to back up will be restored.