Have you run an analysis, yet the word count is much different from what you can see on the page?
Surfer counts all the content that is within the <body> part of your page. This includes any sidebars and the footer, image alt tags, but also hidden content on the page.
You are able to check hidden content, via the SERP Analyzer:
1. Simply click the three dots button on the right side of your URL.
2. After that, please select "Content Outline".
3. At the bottom of the list you will see the hidden content section. Thanks to it you will know which text Google can see on your page, but it's hidden from the regular visitor.