What penis girth is too small for "normal size" condoms?

Simply put,: if it fits snuggly when the penis is erect, it is a good fit. The majority of penis sizes will fit standard condoms. I am curious as to why you are asking this question and if you have concerns about an abnormality you should see your provider and have that discussion.

Condom size: Regular condoms usually work for a girth btwn 4.7 to 5.1 inches. If girth is less than 4.7 inches (119 mm) may need a smaller size. See this site for more detailed information: http://www.condom-sizes.org/condom-size-chart/condom-size-chart