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When looking at usage stats in iOS (data sent/received), are the megabytes/gigabytes in base-10 or base-2?

The docs are not entirely conclusive (since it doesn't address usage specifically) but suggests base-2 is used for iOS device capacities.

So which is it?

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I wasn't able to find conclusive documentation on this so I tested it. I found that iOS uses the base-10 definition when showing usage.

That is, if you send a large file, say 10 mebibytes (10 × 220, or 10485760 bytes), it will report it in megabytes, counting a megabyte as 1,000,000 bytes (not 1,048,576 bytes).

So that 10 MB, shows up as 10.4 MB:

10mb usage

(I'm not suggesting that there's anything nefarious going on here related to billing or data limits.)

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