iOS - archived IPA size does not match what app store reports as size

I am submitting my iOS app to the App Store. In the last version I checked the size by:

Archiving for App Store Sharing the Archive through the Organizer

I checked the size of the resulting file and it was 18.5 MB - compressing this IPA gives me a 18.4 zip file. Yet, when I look at the App Store 开发者_开发问答description for this exact submit, the app store reports 20.5 MB.

I'd like to get this app under the magic 20 MB number, but have been unable to get this tag to report the size Apple is reporting in the App Store.

Has anyone run into this issue?

Thanks!

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@ mark, a friend's company had a similar issue. They suspect apple will add "something" to your .ipa file causing it to increase in size. My friend's company only submits around 17 MB .ipa file to apple and end up with 19 MB + in the app store. Just small enough to still be downloadable without WiFi connection. Hope it helps.

FreeAsInBeer has a good answer that might be the solution of your problem https://stackoverflow.com/a/5264491/1176161