There is a File Size column which shows the size for some folders and files. To get a a detailed list of how much storage each app is taking up, you can do this on your device by tapping Settings > General > Usage, and then tap Show all Apps to see the full list. Then, tap on an app to see more details.
If you see a high amount of “Other” data, the increasing size of “Other” data in iOS has been quite an issue ever since iOS 5, and it’s a bug that Apple doesn’t seem to be addressing. It’s supposed to be under about 1 GB, but if it’s growing to several gigs, Apple’s only recommendation is to restore your device to factory settings which will wipe it clean and remove any of your personal data and settings.
Or, you could try using iExplorer to see if you can at least get the size of “Other” data reduced. Here are some places to look for large files causing the “Other” data to go up:
- In-app downloads – Look in the Media/ApplicationArchives or Media/Downloads folder for any large files to delete.
- Rented movies or TV shows from the iTunes Store that you’ve watched on your device might still be taking up space after the rental time has expired. You can look for any of those in Media/Purchases or Media/iTunes_Control.
- Deleted text message attachments still left on your device. There is a known Apple bug where text message attachments are still left on your device even after you delete the conversation in your Messages app. To look for these, just go to the Backups section > Backups Explorer > MediaDomain/Library/SMS/Attachments folder. If you do end up finding large files in that Attachments folder from a conversation that you know you already deleted, the only way to remove them is if you restore your device to factory settings or Jailbreak your device and gain Root folder (“/”) access since those attachments are stored closer to the root of iOS which Apple prevents anyone from accessing unless you hack (Jailbreak) iOS. The reason that iExplorer’s Backups section can at least display them is because iTunes backs up those files, and the Backups section is extracting the data from an iTunes backup on your computer.