We took two design decisions to guide our development philosophy: to have a low battery overhead and to be lightweight.
The size is 415KB using Proguard excluding Google Play Services sizes as they may vary. We use the following Android Libraries:
Google Play Services Ads
Google Play Services Location
Google Play Services Android Support Library v4
1.5MB size increase on your app.
The download size of the iOS frameworks is bigger since it contains the necessary files to support multiple architectures.