Hello,
our developed Application using Unity is so heavy. It is around 80MB.
compare to other applications in the Market. I think our product is too heavy. I would like to know how to decrease the size into or less than or around 20MB because
some people’s phone has less vacancy of total smart phone size.
anyone knows how to do it? we would like to relase it in Android/IOS market
next week! with smaller size!
Kindly answer this question
Thank you 
Try this
http://docs.unity3d.com/Documentation/Manual/ReducingFilesize.html
Seems like often when this question comes up, the answer is strip your Resources folder of anything not needed and review the build.log
Also try stripping - Unity - Manual: Optimizing the size of the built iOS Player
Reduces the size of an empty scene from 22Mb to 12Mb.
Make sure you don’t have a development build (there’s a checkbox for it in the build menu). Having a dev build includes all debugging symbols which increases the build size by about 60 MB.