HTML payload
Sizes the initial HTML document and flags anything past 500 KB - the threshold where mobile first-paint visibly stalls on 4G.
Page Weight Checker
Measures the size of the initial HTML document and counts declared <script>, <link rel=stylesheet>, <img>, and <iframe> tags. Warns above 500 KB; fails above 2 MB.
Instant audit. No account required.
What the Page Weight audit checks
Three checks, one verdict. Each tile is a primitive your AI agent can read alongside the full JSON payload.
Asset density
Counts the <script>, <link>, <img>, and <iframe> tags so a bundle-splitter regression cannot quietly ship 200 ad-tech scripts.
Render blocking
Surfaces synchronous third-party loads that block first paint - the cheapest performance wins live here.
Page Weight Checker
UpMonitor's Page Weight Checker measures the total size of your website and analyzes your asset composition. By identifying large images, heavy scripts, and bloated styles, you can reduce your page load time and improve the user experience for visitors on mobile or slow connections. Free to use - no signup required.
Audit your website's footprint instantly to identify opportunities for speed optimization.
ℹ️
Page Weight (or page size) refers to the total size of a web page, including all of its linked assets like images, scripts, and stylesheets. Modern web pages often exceed 2MB, which can significantly slow down mobile devices.
What Our Page Weight Checker Validates
Our free auditor provides a breakdown of your page's technical overhead:
✅ Initial HTML Size
Measures the size of the main document your browser downloads first - the HTML payload itself. Pages over 500 KB are flagged as a warning; over 2 MB as a failure. Bloated HTML delays every subsequent paint.
✅ Declared Asset Count
Counts the <script>, <link rel="stylesheet">, <img>, and <iframe> tags the HTML declares. High declared-asset counts correlate with download waterfalls that slow first paint, even when individual assets are small.
🧭 Full Page Weight (Subresources)
For a full bytes-on-the-wire weight that sums every image, script, CSS, and font download, run our Lighthouse+ AI audit. That tool uses the Chrome rendering engine to follow every subresource request and report total bytes + breakdown by type.
Why Page Weight Matters
| Weight | Impact |
|---|---|
| Bloated Images | The #1 cause of slow pages. Unoptimized images can add megabytes of unnecessary data. |
| Heavy Scripts | Excessive JavaScript delays page interactivity (TBT) and drains mobile batteries. |
| Slow Mobile Load | Every 1-second delay in mobile load time can lower conversion rates by up to 20%. |
| SEO Rankings | Google uses Core Web Vitals (including speed metrics affected by size) as a ranking factor. |
Optimization Best Practices
Optimize Your Images
Always use modern formats like WebP or AVIF and ensure images are sized correctly for their display dimensions. Never serve a 4000px image in a 400px container.
Minify and Bundle
Ensure your CSS and JavaScript are minified (removing whitespace and comments) and bundled to reduce the total number of network requests.
Frequently Asked Questions
What is a "good" initial HTML size?
Under 500 KB is ideal for the HTML document itself. We warn between 500 KB and 2 MB, and fail above 2 MB. For the full bytes-on-the-wire page weight (including all subresources), target under 1 MB total - anything over 2 MB feels heavy on mobile, and over 5 MB is effectively unusable on a 3G connection.
Does page size affect SEO?
Yes. Page size directly affects page speed, and page speed is a confirmed ranking factor for both desktop and mobile search results.
How do I reduce my JavaScript size?
Audit your dependencies. Remove unused libraries, use smaller alternatives, and implement lazy loading for scripts that aren't needed for the initial page render.
Set Up Continuous Footprint Monitoring
The free checker above is great for a point-in-time audit, but a single large image upload can ruin your performance.
With a UpMonitor account, you can:
- ✅ Monitor page weight for all your critical URLs 24/7
- ✅ Get alerts if a page exceeds a specific size threshold
- ✅ Track asset count growth over time
- ✅ Receive warnings for unoptimized images or heavy scripts
Also useful for this stack
Pair the audit you just ran with these checkers - the failure modes tend to travel together.
Performance
Measures Time to First Byte (TTFB), total response time, and body size. Grades TTFB as success (≤500ms), warning (≤1000ms), or failure (>1000ms).
Content Compression
Sends two requests - one accepting br/gzip, one accepting identity - to detect Gzip, Brotli, or zstd compression and compute the size savings. Also verifies the Vary: Accept-Encoding header.
Lighthouse+ AI Bridge
Runs Google PageSpeed Insights (Performance, Accessibility, Best Practices, SEO) and layers proprietary audits on top: font self-hosting, SRI, llms.txt readiness, and TTFB classification. Grades on the mobile performance score.
Stop running this audit by hand.
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