Supplemental Index Ratio Calculator uses the simple Google site search (with &filter=0 ) to calculate the total number of pages that are in the total index (main + supplemental).

Then with it adds the ?+-inallurl%3Awww.yoursite.com? extension to find the total number of pages that are in the main index (at the end of this list you will see ?In order to show you the most relevant results, we have omitted some entries ??).

After that the author of the script, Francesco uses some basic math to find out what percentage of pages are in the supplemental index. As you may notice, in the second query there?s a strange operator ?inallurl:www.domain.com? which is not a real Google operator. In reality this operator does not exist, it?s just an hack to have Google trigger his supplemental filter. You can use ?xyz:www.domain.com? and the results will be the same.

The simplest way to use this clever tool - Supplemental Index Ratio Button