Wix Blog: About Blog Post Web Addresses (URLs)

To find the web address (URL) of one of your blog posts, access your live site, click the relevant blog post, and copy the address from your browser's address bar.

Note that your blog post URL looks different when you have a Premium Plan:

Free site: username.wixsite.com/site-address/blog-page-URL/blog-post-URL               
Premium site: yourdomain.com/post/blog-post-URL