There is not a clear cut answer to this question.
However, in general terms, the answer is: ‘the fewer, the better’.
The Marketing Compass recommends that you don’t have more than 20 plugins (there is a WordPress Group there). Even this number feels quite high.
At the time of writing, there are some 50,000 WordPress plugins available.
Popular plugins include Akismet (anti-spam); forms (numerous plugins offer form creation capabilities); Google Analytics (so that you can get analytics working throughout your site): Jetpack (site performance and many helpful features); MailChimp (email marketing); Yoast (which helps with SEO); and WooCommerce (ecommerce).
There are 7 plugins in the above list and it is easy to keep adding new ones. This happens when you think of something that you would like to do within your website. I know, as I have nine WordPress websites.
The challenges of having too many plugins start with website loading speed.
This is a Google SEO ranking factor.
If your website takes longer than 3 seconds to load you have a problem.
Many website visitors will not hang around waiting for your site to appear.
What is more, plugin conflict can occur: i.e. one WordPress plugin can upset another plugin. If this happens to you, it is a good idea to backup your website before you start working on it.
Nigel Temple is a digital marketing consultant.