How to Compress HTML5 ZIP Banners Toward 150 KB
A 150 KB initial payload remains a useful performance target for display ad developers, but it is not the current Google Ads upload ceiling: uploaded HTML5 ZIPs can be up to 600 KB. CM360 accepts larger display creatives and uses polite loading above 150 KB. Here is a production checklist for teams that still need to hit the leaner 150 KB target.
1. Image Compression (Vector vs Raster)
- Save as SVG: Flat illustrations and logos should always be saved as optimized vector SVGs instead of PNGs.
- TinyPNG / WebP: If raster images (photos) are necessary, compress them using TinyPNG or convert assets to WebP format. Set image quality to 75-80% which reduces file size by up to 70% with negligible visual impact.
2. Minify and Combine Code Assets
Remove whitespace, comments, and unused classes from your code. Use command tools like UglifyJS for script assets, and CleanCSS for stylesheets. Always merge separate CSS and JS files into one inside your build folder to save ZIP file index space overhead.
3. Subload Dynamic Resources
Initial load only counts what is inside the ZIP file. For heavy elements (such as dynamic data feeds or auxiliary images), load them asynchronously via JavaScript *after* the page triggers the load event (called polite subloading). Most DSPs allow up to 2.2 MB for dynamic subloads.