We Apple users are picky about our aesthetics. Some of us try to pretend that we aren’t, but we are. Things like app icons matter to us. Apple doesn’t make it easy to customize your iPhone’s look on a system mod level, but luckily there are still jailbreak-free hacks out there to taunt Apple’s need for aesthetic control.

I’m going to walk you through how to manually change app icons on your iPhone without jailbreaking. There are multiple reasons you may want to change an app icon; you think the developer’s icon is ugly, you want a retina display-compatible icon, or you just want to mess with your friend while he’s away from his phone. Here’s how you do it:

Step 1: Download iPhone Explorer (OS X or Windows)

Step 2: Plug in your iPhone over USB and open iPhone Explorer. Navigate to the app you want to change, “Phone/Apps/AppName/AppName.app”

Step 3: If you are using a retina display device, drag the “icon@2x.png” to a folder in the Finder for safekeeping. If you are on a 3GS, 3G or older iPod touch, drag the “icon.png” to Finder for a backup.

Step 4: Find the replacement icon you want to use and name it exactly “icon@2x.png” for the retina display or “icon.png” for older devices (case-sensitive). The file must be a .png file and the size must be 114×114 for retina display and 57×57 for older devices. The image must also be 72 PPI with no transparency and no layers. If you’re using an icon from a designer’s icon container, you shouldn’t have to worry about PPI or the transparency and layers.

Step 5: Delete the default icon and drag your replacement icon to the aforementioned app folder in iPhone Explorer.

Step 6: Reboot your iPhone.

You should now have your replaced icon. If you use a square image, iOS will automatically round the corners to make the icon look uniform to the rest of your homescreen. If you want to make a retina display icon for an app that hasn’t been updated yet, 114×114 is the resolution to use.

Don’t worry about bricking your phone. You don’t have root access to your device, so, you can’t make any changes to crucial elements of iOS. Just make sure to keep a backup of your app’s original icon in case you ever want to switch back.

I tried this process by replacing the default Twitter icon with the Tweetie 2 iPhone icon from Matthew Rex. I use CandyBar on OS X to manage my icons. I exported the icon I wanted to the right resolution through CandyBar.

What app icons will you be changing?