The "storage almost full" warning always seems to appear at the worst moment: while you are trying to take a photo, install an update or open a banking app. A phone with very little free space can run slowly, fail to install updates and refuse to record video. Fortunately, clearing space is usually straightforward if you work through it in the right order.
Step 1: See what is using the space
Both Android and iPhone include a storage screen in the settings menu that breaks usage down by category and by app. Look at it before deleting anything. Typically a handful of items account for most of the space: photos and videos, messaging app media, games, and cached data. Targeting the biggest categories first gives the biggest result for the least effort.
Step 2: Deal with photos and videos
Photos and videos are the most common culprit, especially video. Back them up to a cloud service or a computer first, and confirm that the backup completed. Once you are sure they are safely stored elsewhere, you can remove the local copies; most photo apps have an option to free up device space after backing up. Review the video list sorted by size, as a few long clips can take up gigabytes. Also delete duplicates, screenshots you no longer need and burst photos you did not keep.
Step 3: Clean up messaging apps
Messaging apps quietly save every photo, video and voice note you receive, often in several chats at once. Most have a built-in storage manager showing which conversations use the most space, and letting you delete large files while keeping the text. Group chats that forward large videos are frequent offenders. Clearing these files does not delete your messages, though the media will no longer be available offline.
Step 4: Remove or offload apps you do not use
Go through your app list and remove anything you have not opened in months. Apps keep growing with updates, and some use hundreds of megabytes or more. iPhone has an option to offload unused apps, which removes the app but keeps its data, so reinstalling restores your information. On Android, you can see when each app was last used and uninstall those you have forgotten. Large games are often the biggest single items and are easy to reinstall later.
Step 5: Clear caches carefully
Apps store temporary files, called cache, to load faster. Browsers, streaming apps and social media can accumulate large caches. On Android you can clear the cache for an individual app from its settings page, which is safe and does not delete your account data. Be careful not to choose "clear data" or "clear storage" unless you intend to reset the app and sign in again, since that can remove offline content and local settings.
Step 6: Manage downloads and offline media
Downloaded music, podcasts, videos and maps can take up large amounts of space. Remove offline content you have already finished with, and consider lowering the download quality in the app's settings. Check your Downloads folder as well, since old documents and installers collect there.
Step 7: Consider long-term options
If you constantly run out of space, think about changing your habits rather than cleaning repeatedly. Turn on automatic cloud backup for photos with the option to keep only smaller versions on your device. Keep large game libraries to what you play regularly. Some Android phones accept a memory card, which is a cheap way to store media, though apps usually still need to live in internal storage.
A note on safety
Be cautious of apps promising to boost your phone or clean it with one tap. Many are unnecessary, display aggressive ads or collect data. The tools built into your phone's settings do the same job without the risk. After cleaning, restart your phone and install any pending updates, which often fix performance problems that a full storage had caused.
Work through these steps in order, and you can often recover several gigabytes in under half an hour, without losing a single photo you care about.