Many people delay upgrading to the latest iOS not because they don’t want to or because their devices aren’t supported, but simply because the Settings app tells them that they don’t have enough space to install. What your iPhone or iPad won’t tell you though is that if you plug into your computer by USB and do it the “old fashioned way” you can usually accomplish the upgrade with very little available space.
When upgrading over WiFi, your device needs enough space to download the update, to unzip it, and then to install it. By letting your computer reach into your device through a USB cable, it can essentially remove the old system and swap it for the new one.
Step 1: Backup
Connect your iOS device to WiFi and go to your Settings app > iCloud > Backup (or Backup & Storage) > Backup Now. Let it finish the backup and then confirm the last backup date below the Backup Now button. If your iCloud storage is full, you can change your plan. You get 5 GB for free but 99¢/month will now bring you up to 20 GB.
Step 2: Update
Plug your device into your computer with your USB cable. For better reliability plug it in direct, not through a hub or through your keyboard.
- Mac: Open iTunes. Click the iTunes menu (next to the Apple menu). Choose “Check for Updates…”
- Windows: Open iTunes. Click the Help menu and choose “Check for Updates”. If you don’t have a menu press Ctrl-B to toggle it.
Step 3: Wait
iTunes has to download the entire installer which is well over a gigabyte. This can take an hour or more if you have a slow connection like DSL. But you don’t have to leave your device plugged in this whole time. If you unplug before it finishes downloading, iTunes will save the installer for the next time you plug in. You may need to “Check for Updates” again. Once the installer begins do not, under any circumstances, unplug. If you do you’ll understand why we did that backup in step 1.