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Average Web Page Size Triples Since 2008

Summary: Within the last five years, the size of the average web page has more than tripled, and the number of external objects has more than doubled. The data appears to suggest that the more popular a web page, the smaller the total file size.

The size of the average web page of the top 1000 websites has more than tripled since 2008 (our last update in May 2011 found it had more than septupled since 2003). In the past five years from 2008 to late 2012 the average web page grew from 312K to 1114K (see Figure 1), over 3.5 times larger (Domenech et al. 2007, Flinn & Betcher 2008, Charzinsk 2010, Souders 2012). During the same five-year period, the number of objects in the average web page has more than doubled from 49.9 to 100 objects per page in November 2012.

growth of average web page

Figure 1: Growth of the Average Web Page

Average Web Page versus Survey Size

In the HTTParchive.org site, the data also reveals the average web page for the top 292,880 pages is 1249K in size made of up 86 objects on average. So the top 1000 pages have more objects (100 vs. 86) but less K (1114K vs. 1249K). The top 100 web pages average 955K with 71 requests per page (see Figure 2). So page size appears to be inversely related to site traffic. The more traffic a site has, the smaller the pages.

growth of average web page

Figure 2: Average Web Page Size and Objects vs. Survey Size

The Effects of Caching and other relevant statistics

Charzinski's 2010 paper shows the beneficial effects of caching on performance. Table 1 shows that the average top 500 home page goes from 507K and 64.7 requests upon initial cache-cleared load to 98.5K and 16.1 requests. One average, caching on these popular sites saves 81 percent of the bytes, and 75 percent of the requests.

Other data from the study showed that Akamai still dominates CDNs, with 43.6 percent of the top 500 using Akamai, delivering 22.3% of the initial load, and 25.8 percent of the cached loads overall. Limelight, Footprint, Panther Express and Google round out the top five CDNs. 167 (33.4%) of the top 500 sites employed one or more of the Web 2.0 technologies (XHR, JSON, or GWT Google Web Toolkit).. 38 percent employed from 1-10 web bugs on their home pages.

Table 1: Average Web Page Data S1=empty cache, S2=reload

Load StateHostsConnections Bytes ReceivedElements Retrieved
S1 Ave.7.625.2507K64.7
S1 Max381726.9M31.4
S2 Ave5.510.998.5K16.1
S2 Max27823.5M162

Older Average Web Page Data


The data below is shown for historical purposes.

Anatomy of a Web Page

A web page is made up of a container object (CO) and external objects (EOs). The CO is usually an XHTML file that references EOs such as images, audio, video, and external CSS and JavaScript files. Most non-textual EOs are usually pre-compressed, so you'll only see the benefits of HTTP compression on XHTML and on some CSS and JavaScript files. For more than 60% of web pages, the CO occupies less than 50% of total page size. The average CO takes up about 44% of total page size (Yuan, Li, & Chi 2005).

Therefore, no matter how efficient your XHTML optimization and HTTP compression, the greatest improvement in web page performance that you can expect from XHTML optimization will be less than 50%. For a 300K home page, on average, you'll still need to download at least 150K of EOs, even after optimizing and compressing your textual data. You can see why it is important to optimize your entire web page, including multimedia, in order to make significant performance gains.

Response Time Trends - The Bandwidth Divide

From 2003 to 2009 web page size has more than quintupled and the number of external objects grown by 2.5 times. So narrowband users (56K and ISDN) have experienced slower response times over time. Conversely, broadband users have experienced somewhat faster response times over time. For broadband users the average download time of the Keynote Business 40 Internet Performance Index (KB40) has decreased from 2.8 to 2.33 seconds from Feb. 2006 to Feb. 2008 (see Figure 3 and Berkowitz & Gonzalez 2008).

average kb40 web site performance over broadband from feb. 2006 to feb. 2008

Figure 3: Average KB40 Web Site Performance over Broadband from Feb. 2006 to Feb. 2008 (Source: Keynote Systems, Inc.)

So the increase in the average speed of broadband has more than kept pace with the increase in the size and complexity of the average web page. That is one reason why broadband users expect faster response times. Yet narrowband users have experienced slower response times as web page size has increased.

Average Web Page Characteristics

In a 2006 survey of over 21,500 non-framed web pages, Ryan Levering and Michal Cutler found that the average web page contained 474 words, 281 HTML tags, and 41 links, 10 of which pointed outside the domain (Levering & Cutler 2006). They found that the average web page was 1440 pixels in height, about twice the size of the screen height. When the average web page is opened, more of what the user sees is graphics, not text. Graphics make up most of the objects in the average web page. Graphics cause most of the delays that users experience from object overhead.

Change in the Average Web Page over Time

A subsequent survey in 2007 run for the author revealed changes in the composition of the average web page. Despite the widespread adoption of CSS, the 2007 survey found that 62.6% of web pages still use tables for layout and 32.8% use the font tag for inline style (Levering 2007). In an encouraging trend, the average table depth decreased by half from the 2006 survey, from 2.95 to 1.47. Complex nested tables can cause rendering delays with browsers because tangled tables must be parsed and rendered before your content displays. Between the 2006 and 2007 surveys, the average number of HTML elements per web page more than doubled from 281 to 592.6 elements per page.

Use of JavaScript in the Average Web Page

In the 2007 survey, 84.8% of web pages used the script element. The average size of external scripts was 8,845 bytes uncompressed, and 6,302 bytes compressed. Total script size was 68,812 bytes uncompressed and 49,738 bytes compressed. The average number of external scripts was 7, where 6 of which were unique.

Use of CSS in the Average Web Page

In the 2007 survey, 82.4% used the link tag, and 54.5% used the style tag (with an average of 2.27 style tags used internally). The average size of external style sheets was 6,575 bytes, and 4,457 bytes compressed. The total average style size was 15,175 bytes uncompressed, and 10,347 bytes compressed.

Use of Images in the Average Web Page

Images were used in 91.6% of web pages in the 2007 survey. GIFs were used in 84.6% of web pages, up from 77.9% in 2006 (see Table 2). JPEGs were used in 64.5% of web pages, up from 55.8% in 2006. PNGs were used in 32.2% of web pages, up significantly from 7.2% in 2006. BMPs were used by 0.8% of web pages in 2006. BMPs in particular can be quite large as they are usually not compressed. They should be avoided for Web use.

Image EncodingFrequency 2006Frequency 2007
GIF77.9%84.6%
JPEG55.8%64.5%
PNG7.2%32.2%
BMP0.8%-

Table 2: Image Usage in the Average Web Page (2006 and 2007 surveys)

If the images in the average page were grouped together, the image area would be 49,144 pixels, or an image of 221 by 221 pixels in dimension (see Figure 3).

average aggregated graphic area in average web page

Figure 3: Average Aggregated Graphic Area in the Average Web Page

A large-scale study confirmed these findings with over 75% of HTTP requests resulting from images (Gonzalez-Cañete, Casilari, & Triviño-Cabrera 2007).

The Growth of Multimedia on the Web

The use of streaming media on the Web has increased by more than 100% each year (Li et al. 2005). From 2000 to 2005 the total volume of streaming media files stored on the Web grew by more than 600%. More than 87% of all streaming media is abandoned by users in the first 10 seconds, however, wasting up to 20% of server bandwidth (Guo et al. 2005). While only 3% of server responses are for videos, they account for over 98.6% of the bytes transferred (Gill et al. 2007). In true Pareto fashion, about 10% of the most popular videos on YouTube account for nearly 80% of the views, making caching an appealing performance enhancement (Cha et al. 2007).

Overall, for videos longer than 30 seconds, about 13% of home and 40% of business users experience quality degradation with their streaming media, caused by re-buffering, stream switching, and video cancellation. For sessions longer than 300 seconds, the results are even worse. As broadband penetration has increased, videos have grown in size, bit rate, and duration (see Figure 4).

growth in web video duration over time

Figure 4: Growth in Duration of Web Videos

In 1997, 90% of videos were under 45 seconds in length (Acharya & Smith 1998). In 2005, the median video was about 120 seconds long (Li et al. 2005). By 2007, the median video was 192.6 seconds in duration (Gill et al. 2007). The median bit rate of web videos grew from 200Kbps in 2005 to 328Kbps on YouTube in 2007. So by late 2007, the median video weighed in at over 63MB in file size. On YouTube, the average video size is 10MB, with over 65,000 new videos added every day.

Conclusion

Within the last five years, the size of the average web page has more than tripled, and the number of external objects has nearly doubled. While broadband users have experienced faster load times, narrowband users have been left behind. With the average web page sporting more than 50 external objects, object overhead now dominates most web page delays. Minimizing HTTP requests by using CSS sprites, combining JavaScript or CSS files, reducing the number of EOs, and converting graphic effects to CSS while still retaining attractiveness, has become the most important skill set for web performance optimizers.

Further Reading

Acharya, S., and B. Smith, "An Experiment to Characterize Videos Stored On the Web,"
in MMCN 1998 (San Jose, CA: Jan. 1998), 166-178.
Berkowitz, D., and A. Gonzalez, "Andy: Keynote data for your use,"
e-mail to author (Feb. 8, 2008). Keynote Systems, Inc. provided the graph of the KB40 response time from Feb. 2006 to Feb. 2008. The average web page load time for the KB40 decreased from 2.8 to 2.33 seconds from Feb. 2006 to Feb. 2008.
Cha, M., Kwak, H., Rodriguez, P., Ahn, Y.-Y., and S. Moon, "I Tube, You Tube, Everybody Tubes: Analyzing the World's Largest User Generated Content Video System,"
in IMC 2007 (San Diego, CA: October 24-26, 2007), 1-13. YouTube is estimated to carry over 60% of videos online, serving 100 million videos daily. Simple caching of the most popular videos offloaded server traffic by as much as 50%.
Charzinski, J. "Traffic Properties, Client Side Cachability and CDN Usage of Popular Web Sites"
B. M¨uller-Clostermann et al. (Eds.): MMB & DFT 2010, LNCS 5987, pp. 136-150, 2010. Springer-Verlag Berlin Heidelberg 2010
Domenech, J., Pont, A., Sahuquillo, J., and J. Gil, "A user-focused evaluation of web prefetching algorithms,"
Computer Communications 30, no. 10 (2007): 2213-2224. In 1995 there were 2.3 average objects per page and 25.7 in 2003 (average of two traces).
Flinn, D., and B. Betcher of Gomez.com, "Re: latest top 1000 website data?"
e-mail to author, Jan. 8, 2008. As of January 2008, the average top 1000 home page was 312K in total file size, referencing 49.92 total objects.
Flinn, D., and B. Betcher, "Re: mockup of section in book about slower pages vs higher,"
e-mail to author, Nov. 16, 2007. Gomez surveyed for the author the top 50 retailers for response times, consistency, and composition.
Gill, P., Arlitt, M., Li., Z., and A. Mahanti, "YouTube Traffic Characterization: A View From the Edge,"
in IMC 2007 (San Diego, California: October 24-26, 2007), 20. About 24% of videos are interrupted because of poor performance or poor content quality.
Gonzalez-Cañete, F., Casilari, E., and A. Triviño-Cabrera, "Characterizing Document Types to Evaluate Web Cache Replacement Policies,"
in ECUMN 2007 (Toulouse, France: Feb. 14-16, 2007), 3-11.
Guo, L., Chen, S., Xiao, Z., and X. Zhang, "Analysis of Multimedia Workloads with Implications for Internet Streaming,"
in WWW 2005 (Chiba, Japan: May 10-14, 2005), 519-528.
King, A., "CSS Sprites: How Yahoo.com and AOL.com Improve Web Performance,"
Learn how AOL and Yahoo! use CSS sprites to improve performance for their busy home pages. CSS sprites save HTTP requests by using CSS positioning to selectively display composite background images. To maximize accessibility and usability, CSS sprites are best used for icons or decorative effects. Website Optimization, Sep. 26, 2007.
King, A., "HTTP Compression,"
HTTP compression uses standards-based gzip and deflate compression algorithms to compress your XHTML, CSS, and JavaScript to speed up web page downloads and save bandwidth. Website Optimization, Dec. 4, 2003.
King, A., "Minimize HTTP Requests,"
By combining external files and embedding CSS and JavaScript within your HTML you can minimize the number of HTTP requests required to render your page. Each unique HTTP request requires a round trip to a server, introducing indeterminate delays. Website Optimization, Dec. 17, 2003.
King, A., "Optimize Parallel Downloads to Minimize Object Overhead,"
With the average web page growing past 50 external objects, object overhead now dominates most web page delays. Increasing parallel downloads by using multiple hostnames can realize up to a 40% improvement in web page latency. Website Optimization, Dec. 26, 2007.
King, A., "Suture CSS or JavaScript Files to Reduce HTTP Requests,"
Learn how to "suture" CSS or JavaScript files together before delivery from the server to save HTTP requests. You'll have your organization and eat it too with this server-side approach to merging files. Website Optimization, Oct. 31, 2007.
King, A., "The Average Web Page - Preliminary Results,"
Preliminary results from a 2006 web page survey run for the author by Ryan Levering. OptimizationWeek.com, Oct. 26, 2006.
King, A., "Use Server Cache Control to Improve Performance,"
Configure your Apache server for more efficient caching to save bandwidth and improve web site performance. A web cache reduces latency and improves web site response times. Website Optimization, Oct. 23, 2004.
Levering, R., "RE: revised web page survey,"
e-mail to author (July 27, 2007). In a random survey of 500 pages indexed by Google for the author, 62.6% of pages used the TABLE tag while 85.1% used the DIV tag. Tables nested to an average maximum depth of 1.47, with an average number of 12.57 table tags per page. The average maximum HTML depth was 15.35, demonstrating how DIVs are replacing table nesting.
Levering, R., and M. Cutler, "The Portrait of a Common HTML Web Page,"
in DocEng 2006 (Amsterdam, The Netherlands: October 10-13, 2006), 198-204. Found that the average web page contained 474 words, 281 HTML tags, and 41 links, 10 of which pointed outside the domain. Also found that the average web page was 1440 pixels in height. Table nesting depth was 2.95.
Li, M., Claypool, M., Kinicki, R., and J. Nichols, "Characteristics of Streaming Media Stored on the Web,"
ACM Transactions on Internet Technology 5, no. 4 (2005): 601-626.
Ramachandran, S. 2010, May 26, "Web metrics: size and number of resources,"
Using the Googlebot, Sreeram analyzed both 380 million top sites and 4.2 billion websites to see what the average web page consists of. He found that the average web page is 320K in size, using 43.91 resources per page.Just 66% of compressible bytes were compressed using HTTP compression in the entire Web. 64.3% of the average web page was taken up by images (205.99K of images divided by 320K size of average web page). There were 7 scripts and 3.2 external style sheets. The uncompressed size of the top sites was 477.2K, while the uncompressed size of the average web page (4.2 billion) was 376.7K. Interestingly, the top sites network size (bytes delivered down the pipe) was smaller (312K vs. 320) than the overall average web page, due in part to the increased used of HTTP compression (89% versus 66%). Google, May 26, 2010.
Sounders, S. "The HTTP Archive"
This useful site tracks statistics about how the web was built, including size, page composition, PageSpeed results, and more. Data taken from the Nov. 2012 test run.
Yuan, J.-L., Li, X., and C.-H. Chi, "Understanding the Impact of Compression on Web Retrieval Performance,"
in AusWeb05 (Royal Pines Resort, Australia: July 2-6, 2005), http://ausweb.scu.edu.au/aw05/papers/refereed/yuan/paper.html (Feb. 10, 2008).

By website optimization on 11 Nov 2012 PM

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