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Does anyone know of the story behind this specific UI? I mean I get the base 2 vs base 10 math but whichever route you pick, shouldn't there be consistency? Or is there a story behind this?

2^30 vs 10^9 2^30 vs 10^9

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closed as unclear what you're asking by rk., Charles Wesley, Matt Obee, JonW Aug 27 '13 at 18:11

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question.If this question can be reworded to fit the rules in the help center, please edit the question.

Looking at the screenshot, it looks to me that both numbers are expressed in the same base/unit: 32GB is the initial hardware capacity, and 28.08GB is the remaining capacity after it has been formatted. – Padrig Aug 24 '13 at 6:23
Not clear what you are asking. The operating system takes up space on the disk and that is the reason why you always end up with less than advertised amount. – rk. Aug 25 '13 at 4:06
Not clear what you're asking. Are you implying that the 28.08GB should be GiB? – Bennett McElwee Aug 26 '13 at 1:23

The device reports its Capacity in base-2, whereas 32 GB is the capacity in base-10. You can see 32 GB as an easy to remember number which represents your particular iOS device model.

Apple recently changed OS X to report disk sizes and file sizes in base-10. I don't know why Apple didn't change reporting of iOS devices capacity to base-10 as well. I believe that reporting sizes in base-10 is less confusing for non-programmers.

See this document for more information: How OS X and iOS report storage capacity.

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Technically, giga is the SI prefix meaning 10^9, so the base-10 interpretation should usually be assumed. However, in computing the base-2 near equivalents have always been common, and at least it used to be that any prefix to "byte" was a base-2 measure.

As far as the image is concerned, the 32 GB is the advertised format, the unformatted size of the underlying flash ram. This is a base 10 measure (surprising to me because these are solid state one so I assumed the same physical design drivers for using base-2 would apply). The 28.08 is likely the actual data capacity after formatting the drive, and as pointed out above is a base 2 measure. (It is NOT the unformatted capacity - 32e9 / (1024)^3 is about 29.7, not 28.08.)

The IEC prefixes (GiB, etc.) are relatively new to the game ('99) and my guess is that they'll find adoption in technical literature but not in labeling of "byte" oriented devices.

(Apologies for the earlier mis-information.)

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Note that 32GB ≠ 28.08GiB (it's actually 29.80GiB) so the different numbers don't imply that the bases are inconsistent.

It's likely that the "Capacity" refers to the available formatted space.

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