Where a website app's size comes from
An Android app made from a website has two parts: the runtime — the WebView shell, its resources and (if enabled) the push-notification SDK — and your content. The runtime is roughly 4–5 MB and is the same for everyone. For a URL app that is the whole story: it ships no web content, so choose "Online app" and the estimate is just the shell. For a bundled HTML or ZIP app, your files are added — and how much they add depends almost entirely on what kind of files they are.
Text compresses well. HTML, CSS and JavaScript typically shrink to a quarter of their size inside the package, so a large multi-page site often adds only a few hundred kilobytes. Images and video do not compress at all — they are already compressed — and dominate everything else. Twenty photos at 400 KB each are 8 MB of app, regardless of how small the code is.
What the calculator measures
It compresses your files with the same algorithm Android's packager uses and reports the result by type, so you can see that images are 92% of the total and act on that. It also estimates the Play download, which is smaller than the APK because Play serves each phone only the resources it needs from an App Bundle.
The number that matters most before you build is the upload limit: 5 MB of source content on the free tier, 18 MB with Pro. That limit is on the files you upload, before compression. If the calculator's input total is over it, trim before building rather than after a failed upload.
Making a bundled app smaller
- Convert images to WebP — typically 60–80% smaller than JPEG or PNG with no visible change. The WebP converter does it in batch.
- Resize images to the size they display at. A 4000-pixel photo shown 800 pixels wide is wasted bytes.
- Remove build junk:
node_modules, source maps,.git, design files. Everything in the ZIP ships inside the app. - Drop unused fonts and weights. A single variable font replaces six files.
- Minify last. It helps, but text was already small once compressed.
Or take the other route: if the content is large and changes often, make the app from the site's URL instead and let your server hold the weight. Bundling in depth →