I've been looking at the search analytics report in google search console and I have been looking at my organic CTRs. I rank number one for a lot of keywords, getting about a 4% CTR. Does that sound about right or is it low? We have been number one for that keyword for quite a long time so I'm assuming that it is ok. If it was too low it would probably drop from position one wouldn't it?
I did some research in multiple websites and found that for the first positions CTR normally varies from about 20 to 45%. Check out this website (Breakdown of Google Click-Through Rates in 2017 By Position): https://ignitevisibility.com/ctr-google-2017/ Also this graph from advancedwebranking.com (Data of July 2017).
Its not low its good but its not so acurate in my opinion .But i think you should also try to modify your site a little bit to increase click throught rate and it will help with clients and seo also
4 to 5% CTR for NO.1 position is quite low. However CTR depends on the nature of your site and how users interact with your site. If you are selling something on your site than 4% CTR is quite low. It means that you are not providing relevant content or products.