Hello there, The typical erect penis is usually 5 to 6 inches long with a circumference of 4 to 5 inches. There's more variation in the size of flaccid penises. Some guys are genuinely smaller than that. In rare cases, genetics and hormone problems cause a condition called micropenis -- an erect penis of under 3 inches. Sometimes Peyronie's disease can reduce a guy's size. Depending on the cause and severity of your erectile dysfunction and any underlying health conditions, you might have various treatment options. Your doctor can explain the risks and benefits of each treatment and will consider your preferences. Your partner's preferences also might play a role in your treatment choices.