How can you tell if a man is fertile or not?

Urologist: Have him get a semen analysis - if any problems, have him see a urologist.

Semen analysis: Analysis of semen will tell total number of sperms and motile sperms.Number below reference number will point towards infertility.

Checking mens fertil: You need to do a physical exam and history.Testosterone level if warranted and the most important test is sperm and semen examinantion.To check tha sperm count and motility both are important sperm count and motility is the most important test to check if a man is fertile.