My total vocabulary size is estimated as 23100 words. Based on participations so far, we've already got some decent statistics. Most native English adult speakers who have taken the test fall in the range 20,000–35,000 words. <a href="http://testyourvocab.com/blog/2013-05-08-Native-speakers-in-greater-detail#newMainchartNative" target="_blank" style="color: rgb(119, 119, 119); font-family: Georgia, "Times New Roman", Times, serif; font-size: 16px; background-color: rgb(255, 255, 0);">Click here for a full breakdown by age</a> (opens in new tab/window).
This feels like wow!