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What is the size of the average web page? How have web pages changed over time? Few studies have been done recently until now (King 2003). Ryan Levering, a PhD student at Binghamton University and Michal Cutler from the same school set out to find how the average page is rendered visually (Levering and Cutler 2006).
After surveying the field they wrote their own HTML rendering engine they call WebSeer. Using parts of the Gecko code base Ryan and Michal pieced together a web page rendering engine that parses and interprets web pages on the server. Their report titled "The Portrait of a Common HTML Web Page" shows the results from a psuedo-random crawl from the DMOZ directory and associated pages. The paper focuses on web page area usage, position, and frequency of use. All interesting and useful metrics that we'll report on in a future article, but we wanted to find out size-related data.
After discussing the issue with Ryan, he agreed to run another crawl with his WebSeer tool to get size-related data. These are preliminary results based a couple thousand page run using random pages from the DMOZ directory as "seed" pages. Seed pages are crawled and pages they linked to are also included in the analysis. The preliminary results have the following caveats:
With these caveats in mind, here are the results for the average web page.
|Web Page Component||Size in bytes|
|Average Total HTML size (including internal frame HTML):||25K|
|Average GIF size:||2.9K|
|Average JPEG size:||11.9K|
|Average PNG size:||14.5K|
|Average SWF size:||32K|
|Average Total external script size:||11.2K (37.5K just pages that use it)|
|Average Total external style size:||17K (28.7K just pages that use it)|
|Average Total page size (script/style/flash/images/html):||130K|
HTML page size averaged 25K. For the images, GIFs were the smallest on average, at 2.9K. GIFs are often uses as spacers and simple flat-color icons so the results are no surprise. JPEGs averaged 11.9K, nearly 4 times larger than the average GIF. JPEGs are typically used for smooth-toned images like photographs and product shots. PNGs averaged 14.5K, a bit larger than the average JPEG. With their superior horizontal and vertical compression scheme, we've found PNG-8s to be more efficient than GIFs in most cases.
For the external scripts and styles, the lower figure (11.2K for all pages' external scripts for example) is the average for all pages tested, whether they used scripts or not. For those pages that did use external scripts, the scripts averaged 37.5K uncompressed in total. The average total external CSS (for pages that used external CSS files) was 28.7K uncompressed.
Although these are preliminary results, the data gives us an idea of the size and composition of the average web page. Without compression and CSS images, the average web page is about 130K in size, with a 25K HTML file, small GIFs and larger JPEGs, PNGs, and SWF files when used. For those pages that use them external scripts averaged in total 37.5K and external style sheets averaged in total 28.7K per page. The HTML figures are in line with the home page trend I reported on in Speed Up Your Site where the average home page HTML file size grew from 8,297 to 28,290 bytes from 1996 to 2002. However as web pages become more complex, each individual component adds size and HTTP requests to the total page payload.
Andy King is the founder of five developer-related sites, and the author of Speed Up Your Site: Web Site Optimization (http://www.speedupyoursite.com) from New Riders Publishing. He publishes the monthly Bandwidth Report, Optimization Week, and Speed Tweak of the Week.
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Last modified: May 02, 2008