First up are your messages. Threads filled with GIFs, memes, videos and photos can take up a ton of space. In iOS, you can change how long your phone stores messages so it clears out those old threads automatically, without you having to do it.
Head to Settings, Messages, and Keep Messages. Once there, set how long you want to keep messages before they self-destruct. If you want to keep the text but delete attachments, head instead to Settings, General, then iPhone Storage, scroll down to Messages and then tap Review large Attachments. This screen will show you all the big files.
Android’s Messages app doesn’t have a setting like this, but you can swipe left or right on a message thread in Messages to archive old threads. Most third-party apps, including WhatsApp and Facebook Messenger, have some means to clear out old messages.
The biggest storage hogs on your phone are likely photos and videos. Back them up to an online cloud backup service like Apple iCloud, Google Photos or Amazon’s Prime Photos. Once you back up the photos, you can delete them from your phone and access them remotely through the backup service.
If you’re still short on space even after taking those steps, the culprit might be an app that’s hoarding data. Podcasts, music services and video apps are usually the biggest offenders. To see what’s taking up space in iOS, head to Settings, General, then iPhone Storage. On Android, pull down the notification shade, tap the cog and then select Storage. This screen displays a list of all the apps on your phone.
For example, the Amazon Prime Video app on my phone takes up two gigabytes of space, even though I’ve never downloaded a video. To clear out app data on an iPhone, tap the app from the Storage screen and then tap Offload. Once the phone is done deleting everything, tap Reinstall. On Android, tap the app name and then the Clear Cache button.
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A version of this article appears at Wirecutter.com.