Short answer: Settings â Storage on Android, or Settings â General â iPhone Storage on iOS. Then empty the Recently Deleted folder first â that alone recovers more space than anything else for most people.
Where to look
Android: Settings â Storage. Shows a bar chart by category â Apps, Images, Videos, Audio, Documents, System. Tapping any category drills in. Samsung puts a similar view under Device care â Storage.
iPhone: Settings â General â iPhone Storage. Lists every app by size, largest first, with automatic recommendations at the top. The coloured bar at the top breaks it down by type.
Both take several seconds to calculate the first time you open them.
Why your capacity never matches the box
A 128 GB phone typically shows 112â118 GB available. Two separate causes, both unavoidable:
Binary vs decimal. Manufacturers count 1 GB as 1,000,000,000 bytes. The operating system counts it as 1,073,741,824. That is a 7% difference before anything is installed â 128 "marketing GB" is 119 real GB.
The OS itself. Android or iOS plus preinstalled apps takes 8â15 GB, and more on heavily customised skins.
Neither is recoverable and neither is a fault.
The cleanup that actually works, in order
1. Empty Recently Deleted. This is the biggest and most overlooked win. Deleted photos and videos sit in a bin for 30 days.
- iPhone: Photos â Albums â Recently Deleted â Delete All
- Android: Google Photos â Library â Bin â Empty bin
2. Deal with videos, not photos. A minute of 4K video is roughly 350 MB â around 150 photos. Sorting your gallery by size and reviewing the ten largest videos usually frees several gigabytes in two minutes.
3. Clear messaging app media. WhatsApp, Telegram and similar apps store every received image and video indefinitely. WhatsApp â Settings â Storage and Data â Manage Storage sorts by size and is often the single largest app on a phone.
4. Offload unused apps rather than deleting them. iPhone: Settings â General â iPhone Storage â Offload Unused Apps removes the app but keeps its data, so reinstalling restores everything. Android's equivalent is archiving in the Play Store.
5. Remove downloaded media. Offline Spotify albums, Netflix downloads, offline Google Maps regions and podcast backlogs are invisible in a normal file browse but can run to many gigabytes.
6. Clear browser cache. Chrome and Safari accumulate hundreds of megabytes.
Understanding "Other" and "System Data"
This category alarms people because it can reach 20 GB or more and there is nothing obvious to delete.
It contains caches, logs, streaming buffers, mail attachments, Siri voices, font files and anything the OS cannot attribute to a specific app. It is not a leak and it is not corruption.
What actually reduces it:
- Restart the phone. Clears temporary files. Surprisingly effective.
- Clear Safari/Chrome cache and website data.
- Clear the cache of streaming apps specifically â these are the worst offenders.
- Wait. Both systems reclaim this space automatically when storage runs low.
What does not reduce it: cleaner apps, which mostly delete things the system would have cleared anyway.
Photos: cloud vs device
The highest-leverage change for most people is how photos are stored.
- iPhone: Settings â Photos â Optimise iPhone Storage. Full-resolution originals go to iCloud, smaller versions stay on device. Requires enough iCloud storage.
- Android: Google Photos â Settings â Back up â then use Free up space to remove local copies of already-backed-up photos.
This routinely recovers 20â50 GB on a phone with a few years of photos. The trade-off is that viewing an old photo at full resolution needs a connection.
SD cards, if you have a slot
Fewer phones support them now, but if yours does:
- Move photos, videos, music and documents â these work fine from a card
- Do not move apps unless you must; app performance on a card is noticeably worse
- Buy A2-rated cards for app storage, and a reputable brand â counterfeit cards reporting false capacity are common
- Remember a card is not a backup; it fails more often than internal storage
Keeping on top of it
- Check storage monthly, not when the phone is already full
- Keep at least 10% free â both platforms slow down and behave unpredictably when nearly full
- Turn on automatic photo backup so local deletion is safe
- Review the largest apps quarterly rather than deleting small things
A device settings app shows the breakdown alongside RAM, battery and system information, which is useful when you are trying to work out whether storage is actually your bottleneck.
