Google’s site command, i.e. site:www.domain.com, is known by savvy webmasters and SEOs as not a great measurement of the total pages Google has indexed of your site.

Of course, for small sites, it works pretty well, but for really large dynamic sites, the result count presented through using a site command can be misleading or a really bad estimate.

Google’s Matt Cutts said this himself back in December 2012 in video answer.

Now, Enrico Altavilla shared results of a 410 experiment he is running which gave him even less confidence in using the site command. Enrico Altavilla wrote:

He then shares how he tried to measure this by using 410 status codes to remove pages and document the numbers returned using the site command over time.

He says that you can “use it to monitor a trend over time but the actual numbers are almost meaningless.” Most would agree with that but look at his chart:

Using Google Webmaster Tools should be way more accurate, either through the sitemap report or the index status report.

Forum discussion at Google+.