Page Size Checker
Analyze page weight, resource breakdown, third-party scripts, and unused code with real Lighthouse data.
Why Page Weight Matters
Page weight directly impacts Largest Contentful Paint (LCP) and Time to Interactive. The median mobile page now weighs 2.5 MB, growing ~10% per year. But median doesn't mean good — sites in the bottom 25th percentile (under 1 MB) consistently score higher on Core Web Vitals.
JavaScript is the most expensive resource type: every 50 KB of JS costs ~100ms of parse/compile time on mid-range phones. Images are cheaper byte-for-byte since they don't block the main thread, but unoptimized images are the largest contributor to total page weight.
Page Weight Benchmarks (Mobile)
Source: HTTP Archive, 2025-2026 mobile data
How to Reduce Page Weight
Optimize Images
Use AVIF (50% savings over JPEG) or WebP (30% savings). Serve responsive sizes with srcset. Lazy-load below-fold images.
Trim JavaScript
Tree-shake unused code. Code-split routes. Audit npm dependencies — many bundles ship 30-50% unused code.
Enable Brotli
Brotli compresses 15-25% better than gzip for text resources. Most CDNs and reverse proxies support it out of the box.
Audit Third Parties
Third-party scripts average 30-50% of total page weight. Remove unused trackers, defer non-essential scripts, and use lightweight alternatives.
Variable Fonts
Replace multiple font files with a single variable font. Subset to only the characters you need. Use WOFF2 format.
Set Budgets
Set a performance budget (e.g., 200 KB JS, 500 KB images). Use Lighthouse CI to enforce budgets in your CI pipeline.
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Frequently Asked Questions
01What is a good page size?
Under 1 MB total transfer size is excellent. 1-2 MB is acceptable for content-rich pages. 2-3 MB is heavy and will impact mobile users. Over 3 MB is considered poor — the median web page is around 2.5 MB on mobile, but that doesn't mean it's good. Aim to be in the bottom 25th percentile.
02How does page size affect performance?
Larger pages take longer to download (hurting LCP) and require more CPU to parse JavaScript (hurting TBT and INP). 50% of mobile sites take over 14s to become interactive, with a median mobile Total Blocking Time (TBT) of 1,916ms. Every 100 KB of JavaScript costs roughly 100ms of parse time on mid-range phones. Images are less CPU-expensive than JavaScript byte-for-byte.
03What is the average web page size in 2026?
According to HTTP Archive data, the median mobile page weighs about 2,559 KB (~2.5 MB), growing roughly 10% year-over-year. Desktop median is about 2,862 KB. At the 90th percentile, pages exceed 8 MB. JavaScript and images are the two largest contributors.
04Does page size affect SEO?
Indirectly, yes. Page size impacts Core Web Vitals (LCP, INP, CLS). While only 48% of mobile sites pass all CWVs and speed has a weak direct correlation to organic rank, a 1-second delay can lead to a 7% drop in conversions. Very large pages also affect crawl budget and have a larger carbon footprint — a median 2.5MB page correlates linearly with higher energy use in data transfer.
05What is the difference between transfer size and uncompressed size?
Transfer size is the actual bytes sent over the network after gzip or brotli compression. Uncompressed size is the raw content before compression. Text-based resources (HTML, CSS, JS, JSON) typically compress 3-5x. Images are already compressed so transfer and uncompressed sizes are similar.
06How do I reduce my page size?
Compress images with AVIF/WebP (30-50% savings over JPEG). Tree-shake and code-split JavaScript. Remove unused CSS. Enable brotli compression on your server. Lazy-load images below the fold. Audit third-party scripts — they often account for 30-50% of total page weight.
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