My website is over 1 year old and out of the 181 pages in the sitemap, google has indexed 63 so far. Is that normal? For comparison, I would like you to include the number of pages in your sitemap and the number of pages indexed by google. Thanks in advance.
In my experience this is pretty normal, the numbers google present in the webmaster tools are always a little off what I expect to see. However - do check your page titles and descriptions are not throwing up any duplication errors, or are too short - there is a section in webmaster tools were you can see this.
I have or help with a number of websites in a variety of "states" in regards to how much of their actual pages get indexed by Google according to their webmaster tools dashboard. I really do not think it's a matter of size but may be a matter of age, content on page, and sitemap (xml) usage/submission, but of course "authority" helps too I believe. For most of my content rich sites, Google has indexed all or all but a few of the pages (620/642; 130/130; 746/755; etc.), but for some of the commercial sites' pages, the percentage tends to drop below 80% - however, the lack of content does not hinder these pages (many product pages and images indexed) as much as the programming and scripting involved in some of them I think. More to the point of your inquiry, yes, I think it is quite "normal" for Google to only, especially initially, index and rank into its SERP only a portion of a site's web pages. What is your URL? What type of site / content? Using and submitting an xml sitemap?
Thanks for the insight on indexing wrmineo, I too have wondered why google does slow site indexing. Only about 75% of my pages have been indexed on most of my sites.
Why such low percentage of indexing ?? Does the indexing influence the Google custom search functionality? For example, if only 50% of my site is indexed, when a user uses Google custom search on my site, will it only search that 50% of the site ?