How does Google calculate the speed of website?

As you know, Google has more speed in the evaluation criteria and rank web pages . So Google has calculated that score based on criteria like?

Google relies on the following criteria:

Optimize the order of styles and scripts Small Inline CSS Minify CSS Avoid CSS @ import Small Inline JavaScript Leverage browser caching Optimize images Defer parsing of JavaScript Minify HTML Minify JavaScript Specify a cache validator Serve resources from a consistent URL

Specify a Vary: Accept-Encoding header Serve scaled images Specify image dimensions Specify a character set Combine images into CSS sprites Request size Minimize Minimize redirects Make landing page redirects cacheable Avoid bad requests Prefer asynchronous resources Remove query strings from static resources Put CSS in the document head

How many points of your site?
One way to find out how many points you get from Google, by using an extension of Chrome

1. 1. Type about: flags up the address bar bar
2. 2. Scroll down and see Experimental Extension APIs (API extension test), and click Enable (on)
3. 3. Bottom of the page and see the relaunch Now (Restart) - Chrome will automatically restart
4. 4. Install the extension Page Speed
5. 5. On your website, right click, select Propertise (Check element)
6. 6. There is a tab, go to Page Speed ​​tab and click on Run Page Speed ​​on the left
7.  

Only a few seconds later you can see the speed with which Google has calculated for you. From this point on, you just do steps 5 and 6 are able to view the speed of Google from all different websites.

If you use the W3 Total Cache plugin (a plugin of WordPress). You can configure at the General tab (at the near end). And then you can update at any time Dashboard.