There is no standard limit for the number of guinea fowl that are recommended to keep at any one time. But there are certain factors that can guide your decision.
If you are getting guinea fowl for ornamental purposes, you may get just 2: a male and a female.
If you want eggs from a domestic bird, guinea fowl should not be the first on your mind. Guinea fowl lay an average of 100 eggs per year.
If you keep them in a small or restricted area, they will get stressed. As a rule, you should have a space that offers 2-3 square feet per guinea fowl.
But remember, keeping a single guinea fowl could be worse if it is lonely and stressed with no other animals to keep it company.