How much storage do I need on an iPhone?
Updated October 20, 2026 by madebykamal
Start from the phone you have now: Settings, General, iPhone Storage shows how much you use and what uses it, and the new phone needs that much plus room to grow. Apple lists the iPhone 17 in 256GB and 512GB, and the iPhone 18 Pro and 18 Pro Max in 256GB, 512GB, 1TB and 2TB. Every size holds less than its label, because iOS and Apple's own apps take about 12GB to 24GB.
The storage sizes Apple lists for each model
The sizes below come from Apple's own technical specifications pages, and on all of these models 256GB is the smallest option. The iPhone 17 Pro and 17 Pro Max no longer appear in the lineup on Apple's iPhone page, which now lists the iPhone 18 Pro, iPhone Air, iPhone 17, iPhone 17e and iPhone 16 alongside iPhone Duo, but their tech specs pages on Apple Support still list their sizes.
- iPhone 17: 256GB or 512GB.
- iPhone 18 Pro: 256GB, 512GB, 1TB or 2TB.
- iPhone 18 Pro Max: 256GB, 512GB, 1TB or 2TB.
- iPhone 17 Pro: 256GB, 512GB or 1TB.
- iPhone 17 Pro Max: 256GB, 512GB, 1TB or 2TB.
Why the phone never shows its full capacity
Apple's footnote on the iPhone 17 and iPhone 18 Pro specifications says available space is less than the capacity and varies. A standard configuration uses approximately 12GB to 24GB, including iOS 27 and Apple apps that can be deleted. Within that, Apple Intelligence on-device models use approximately 7GB and can be deleted if you turn Apple Intelligence off (turning it back on downloads them again), and the Apple apps you can delete use about 4.5GB. Apple adds that this changes with software version, settings and model.
Size it from the phone you have now
Your current phone is the most useful guide you have. Open Settings, tap General, then tap iPhone Storage. Apple says this screen shows recommendations and a list of apps with the space each one uses.
- Note how much of your current capacity is in use, and which category is largest.
- Think about how that will change: more years of photos, a better camera recording larger video, more apps.
- Add Apple's 12GB to 24GB for iOS and its apps, since that comes off the new phone too.
- If you are already near full and you keep everything, choose a size above the one you have. If you have plenty left after a few years, the same size is likely to work again.
What takes the most space
Apple's storage article sorts usage into Apps (installed apps and their content, files in On My iPhone and Safari downloads), Photos (photos and videos in the Photos app), Media (music, videos, podcasts and voice memos), Messages (messages and their attachments) and Mail, with System and Other for iOS and items you cannot remove.
Video is where the size question is usually decided. Apple's iPhone User Guide says faster frame rates and higher resolutions result in larger video files. The iPhone 17 records 4K Dolby Vision at up to 60 fps, and the iPhone 18 Pro models go up to 120 fps on the Fusion Main camera, so the same minute of video takes more space at the higher settings. The formats are in Settings, Camera, Record Video.
ProRes changes the math on Pro models
Apple says ProRes files are up to 30 times larger than HEVC files, one of the two formats the camera uses when ProRes is off, and that you need at least 10 percent of the phone's storage free to record in ProRes. The iPhone 18 Pro specifications list ProRes recording up to 4K at 120 fps with external recording, and Apple's ProRes article says ProRes at 4K 60 fps and 4K 120 fps on the 17 Pro needs an external storage device.
If you plan to record ProRes to the phone itself and keep the clips there, the 1TB and 2TB sizes on the Pro models give that video the most room. If you record ProRes straight to an external drive connected with USB-C, as Apple's article describes, the clips are stored on that drive instead of the phone.
How Disky helps you decide
Disky is an iPhone storage cleaner that shows a forecast of how many days until your phone is full at this month's rate, before you clear anything. That rate is a practical input for this choice, because it shows how quickly your own habits fill a phone of the size you have. Disky also finds duplicate and similar photos, screenshots and large videos, and it can compress a video instead of deleting it, which can buy time on the phone you have.
Questions people ask
Is 256GB enough for an iPhone?
256GB is the smallest size Apple lists for the iPhone 17, 17 Pro, 18 Pro and 18 Pro Max. Whether it is enough depends on your use: check Settings, General, iPhone Storage on your current phone, and remember iOS and Apple's apps take about 12GB to 24GB.
How much storage do I need for the iPhone 18 Pro Max?
Apple lists it in 256GB, 512GB, 1TB and 2TB, the same sizes as the iPhone 18 Pro. Size it from what your current phone uses, and consider 1TB or 2TB if you plan to record and keep ProRes video on the phone.
Does 4K video take up a lot of storage?
Yes, more than lower settings. Apple says faster frame rates and higher resolutions make larger files, and ProRes files are up to 30 times larger than HEVC files. You can change the format in Settings, Camera, Record Video.
Related
- Why iPhone Storage Is Still Full After Deleting Photos
- Best storage cleaner apps for iPhone in 2026
- Disky - Storage Maxxing
Sources
- https://www.apple.com/iphone-17/specs/
- https://www.apple.com/iphone-18-pro/specs/
- https://support.apple.com/en-us/125090
- https://support.apple.com/en-us/125091
- https://www.apple.com/iphone/
- https://support.apple.com/en-us/108429
- https://support.apple.com/guide/iphone/record-a-video-iph61f49e4bb/ios
- https://support.apple.com/en-us/109041