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HTML Size Checker

Check raw HTML file size, estimated gzip size, and inline CSS/JS bloat with recommendations to reduce it.

HTML Size CheckerGratisTechnical SEOChecks a live URL

Enter a public URL. We fetch the live page and analyse what search engines and AI crawlers see.

Key features of the HTML size checker

  • Measures raw HTML document size in bytes and KB
  • Estimates compressed (gzip/brotli) transfer size
  • Checks whether HTTP compression is enabled on the server
  • Highlights whether size exceeds recommended thresholds
  • Provides specific recommendations for reducing HTML size

How to use the HTML size checker

  1. Enter the page URL

    Paste the URL of the webpage you want to measure.

  2. Run the check

    Click 'Check HTML Size' to fetch the page and measure the HTML document size.

  3. Review size metrics

    See the raw HTML size, compressed size, and compression ratio.

  4. Check compression

    Verify that gzip or Brotli compression is enabled to reduce transfer size.

  5. Reduce HTML size

    Minify HTML, move inline CSS/JS to external files, remove HTML comments, and reduce unnecessary markup.

What is an HTML size checker?

The HTML Size Checker measures the size of a webpage's raw HTML document — the initial response from the server before any external resources load. It checks the uncompressed HTML size, estimated compressed size with gzip, and Time to First Byte (TTFB) implications of large HTML documents.

The initial HTML document is the most critical resource for page performance — everything else depends on it. Large HTML documents delay the start of rendering, increase TTFB, and make Google's servers work harder to crawl your page. Keeping HTML lean is a foundational performance best practice.

Why use an HTML size checker?

A bloated HTML document is often filled with inline CSS, embedded JavaScript, base64-encoded images, and repetitive markup. Reducing HTML size directly improves TTFB, enables faster initial rendering, and makes pages more crawlable — all of which contribute to better Core Web Vitals and SEO performance.

HTML size checker: frequently asked questions

Something else? Ask the team

What is a good HTML page size?

For optimal performance, HTML documents should ideally be under 100KB uncompressed. With gzip compression, most HTML pages compress to 20–40% of their original size, significantly improving transfer speed.

Does HTML size affect SEO?

Yes. HTML size affects TTFB (Time to First Byte) and initial rendering speed, which are components of Core Web Vitals. Google's crawlers also have a download limit per page, so very large HTML may not be fully crawled.

What makes HTML files large?

Common causes: inline CSS and JavaScript (should be external files), embedded base64 images, HTML comments left in production code, repetitive inline styles, large server-generated template markup, and excessive whitespace.

What is gzip compression?

Gzip is a compression algorithm that reduces file transfer sizes. Most web servers can automatically compress HTML, CSS, and JS files with gzip before sending them, reducing file sizes by 60–80%.

How is HTML size different from total page size?

HTML size refers only to the initial HTML document. Total page size includes all referenced resources (CSS, JS, images, fonts). HTML size affects TTFB and initial render; total page size affects full load time.

Each one opens on its own page and works straight away, with no sign-up.

Ontdek meer gratis tools:Schema GeneratorMetatag GeneratorLLMs.txt GeneratorBrowse all free tools

Meer AI-vermeldingen winnen?

HTML Size Checker is one piece of the puzzle. See how ChatGPT, Gemini, Perplexity, and Google AI Overviews actually view your brand, and get a prioritised list of fixes, with a free AEO & GEO audit from AI Rank Lab.

One check is a start. The audit checks the whole site.

Voer een gratis AEO- en GEO-audit uit or Bekijk prijzen.

  • Scores SEO, answer-engine (AEO) and generative-engine (GEO) readiness
  • Lists the fixes, page by page
  • Then track whether ChatGPT, Gemini, Perplexity and Google AI Overviews cite you
fieldnote.app4,571 credits

Site audit

fieldnote.app · SEO, AEO and GEO

Illustrative data
SEO
82
+6
AEO
64
+11
GEO
58
+9
Pages
48
Fixesby impact
  • /pricing · Missing H1High
  • /blog/guide · No FAQ schemaMedium
  • /llms.txt · Not foundMedium
  • /about · Meta description too longLow

See where your whole site stands

Paste your site. The free audit scores it for SEO, answer engines and generative engines, with the fixes.

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