Teams treat application size as an engineering hygiene issue. In markets where storage is limited and data costs money, it is a business metric. A user who taps install and watches a progress bar crawl has a decision point that a smaller app never gave them.
Android's app bundle format handles much of this automatically, delivering only the resources a given device needs rather than everything for every screen density and architecture. If you are still shipping a universal APK, switching is the single largest reduction available and costs almost no effort.
After that, the usual culprits are images and libraries. Uncompressed assets, multiple icon sets, and fonts with full character coverage add up quickly. So do dependencies pulled in for a single utility function — analytics SDKs in particular have a habit of bringing large transitive trees.
Measure before cutting. Both platforms provide an analyser that shows what occupies the space, and the distribution is usually surprising. Teams routinely spend a week optimising code that accounts for a fraction of the binary while an asset directory nobody remembered holds the bulk.
Dynamic delivery lets you ship features on demand rather than in the initial download. For a feature used by a minority of users — an advanced report, a rarely used flow — this moves weight out of the install without removing the capability.
There is a second-order effect worth knowing. Update size matters as much as install size, because a user who declines updates eventually runs a version you no longer support. Smaller, more frequent updates keep more of your user base current than large occasional ones.
