On the side of the iPhone packaging, Apple defines 1GB as 1,000,000,000 bytes (rather than 1,073,741,824 bytes), so you end up missing 9,438,953,472 bytes (~9GB) calculating it this way for 128GB of space (128,000,000,000 bytes is ~119GB).

My iPhone says that it has 113GB of capacity, but it should be 119GB, so where did the other 6GB disappear to?

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    Minor nitpick, but you're conflating metric prefixes and binary prefixes. 128 GB is ~119 GiB. – Cornstalks Mar 9 '16 at 1:12
  • Friendly nitpick of your nitpick: JEDEC memory standards. – Andrew Larsson Mar 9 '16 at 4:54
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    @AndrewLarsson JEDEC is an American industry organization - nobody ever accused Americans of being reasonable when it comes to units, nor industry organizations (focused on semiconductors to boost) of having foresight and logical and forward-thinking specifications. SI is the international standards system, whose definition of kilo dates back to 1799, long before JEDEC existed. – phihag Mar 9 '16 at 6:49
  • You're looking at the difference between gigabytes (GB) and gibibytes (GiB or in some cases Gb). The gibibyte is 1,073,741,824 bytes; the gigabyte is 1,000,000,000. – ArtOfCode Mar 9 '16 at 9:00
  • @phihag Just because a standard is older doesn't mean it makes more sense :) And it's not like the international standard dates to 1799 - that's just when the term was codified in France. You could just as easily say that it dates to ancient greece, where "kilo" already meant "thousand" thousands of years ago :) Finally, byte is not an SI unit, and neither is it SI derived. While there's certain benefits to having common unit prefixes, we still use hours and days, don't we? :) – Luaan Mar 9 '16 at 11:29

The other 6 GB are OS itself. The given capacity is a value for the physical storage that the phone has, not the amount that can be used by the owner. iOS is about 6 GB in size on its own.

Also, the formatted capacity is less than the size of the chips that are manufactured into the device. It's in a very small footnote at the bottom of the tech specs for each iOS device. Typically note #1

picture of footnote

As you can see on the following link, each OS differs between versions, device type and device size so the gap in specs to usable space isn't a fixed constant.

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    Why doesn't Apple shows that capacity is 119GB and 6GB is used. Just like on Macs. Can you confirm that iOS excluded from capacity? – user1561346 Mar 8 '16 at 22:17
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    Using the larger value makes the phone seem to have more storage than it really does. A similar question is asked in this thread. – diplomaticDeveloper Mar 8 '16 at 22:19
  • I do think that this is probably the right answer. But I can't find any confirmation at the moment. By the way, sometimes you can see on absolutely new devices that about 1GB is used. – user1561346 Mar 8 '16 at 22:38
  • @user1561346 I'll direct you to Ask Different Chat for discussions on why Apple does X - it leads to speculation and generally is off topic for the main site. – bmike Mar 8 '16 at 22:39
  • @bmike I don't ask why Apple does something. The question is where did the space disappear. I just wanted to make it clear whether it's some kind of strange storage formatting or just iOS size is deducted from capacity. – user1561346 Mar 8 '16 at 22:53

I believe iOS displays capacities in base-10 values as well, so iOS would show the raw space as 128GB. The 15GB difference (128-113) is due to both iOS and formatting, not a discrepancy between base-2 and base-10.

  • This has been my experience - a combination of losses to the filesystem, usage by system mandated files, and perhaps a very small storage controller component should make up the total. – bmike Mar 9 '16 at 1:27

To simply put, it is used by the Operating System. All that code would have to go somewhere, right? Also, if you notice, with every new major update they try to cut down that space. Even if you write a simple program, it would take up some memory from your computer. It is the same concept for cell phones as well.


The OS needs that space, operating systems take up lots of space

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