HTML document sizeWhat it checks and how to fix it

What it checks

Measures the size of the page's rendered HTML document, uncompressed. Passes up to 200 KB and warns above it (200 KB of raw HTML is roughly 50 KB on the wire once compressed).

Why it matters

The HTML document is the first thing the browser downloads and nothing else can start until it arrives and is parsed. Bloated HTML, usually from inlined data, huge SVGs or framework state embedded in the page, delays first paint, eats into crawl budget and makes every visit heavier.

How to fix it

Find what is inflating the document (view the page source and sort by size) and move it out:

• Large JSON blobs from frameworks (__NEXT_DATA__, hydration state): send only the data the page needs, or fetch the rest on demand.
• Inline SVGs repeated many times: use an SVG sprite with <use> or an external file.
• Base64-encoded images and fonts in data URIs: serve them as separate, cacheable files.
• Long lists and tables: paginate them or load them on demand.

<svg><use href="/icons.svg#check"></use></svg>

Also make sure the HTML is served compressed (gzip or Brotli).