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Thursday, February 7, 2013

Using WebP to Improve Speed

Since speed is critical for a good experience when using the web, at Google we’re always exploring ways to make the web faster. As it turns out, one of the biggest bang-for-the-buck ways to do that is by replacing JPEG and PNG images with WebP. WebP offers significantly better compression than these legacy formats (around 35% better in most cases), and when you consider that over 60% of typical page sizes are images, the benefits can be substantial. WebP translates directly into less bandwidth consumption, decreased latency, faster page loads, better battery consumption on mobile, and overall happier users.

Case in point: the Chrome Web Store uses many large promotional images and tiles on its home page, making it a very heavyweight page. The team was eager to find ways to improve its speed, without sacrificing the user experience or giving up image quality. WebP to the rescue!

By converting PNGs and JPEGs to WebP, the Chrome Web Store was able to reduce image sizes by about 30% on average (here’s one sample image in WebP at 8.3kB and JPEG at 32kB). Given the number of requests Chrome Web Store serves, this adds up to several terabytes of savings every day.

For users, the rubber meets the road when it comes to how fast the page loads though. On this score, with WebP we were able to reduce average home page load time by nearly one-third — a huge benefit for our users.

To implement WebP, the team first added transcoding support to the image request pipeline; then at runtime the site checks whether the client browser supports WebP and requests the WebP version for each image when it does. The effort to implement it turned out to be not much work for a lot of benefit.

To find out more about how you can make your site faster, visit our Make the Web Faster site and dive into WebP.