Page weight, also called page size, is the total number of bytes a browser transfers to load a page. It is usually reported as transfer size (after compression) and sometimes as uncompressed resource size.
Why it matters
More bytes mean more time on slow or metered connections, higher data costs for visitors and more load on your servers. Weight also affects CPU work: a 500 KB JavaScript file compresses well but must still be parsed and executed in full. Images typically account for the largest share, followed by JavaScript.
Example
A breakdown from a browser's network panel:
Images 1.4 MB
JavaScript 620 KB (compressed)
CSS 85 KB
Fonts 120 KB
HTML 30 KB
Total 2.26 MBSetting a performance budget, such as "no more than 1.5 MB on first load", turns this into an enforceable limit in a CI check.
Common mistakes
- Looking at weight alone. Ten small blocking requests can be slower than one larger lazy-loaded one.
- Measuring only the initial load and ignoring bytes pulled in later by interaction or scrolling.
- Comparing compressed and uncompressed numbers from different tools.
- Forgetting third-party scripts, which are often a large part of the total.
Related
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