rstermer

I'm making some mortise and tenon joints. The tenons will be made on my router table. The mortises will be 1/2" wide and will be made on a mortising machine. I am wondering if there is any guidance as to how much smaller than the mortises the tenons should be to get a good fit. For example, if the mortises are 0.50", should I work toward a tenon of 0.48", or is it something one must do by feel? The material is pine.

Thanks in advance for your thoughts.
Bob S