How to measure? There are several methods, but the most common for research studies, and the one I go by is to simply lay a ruler across the top of your fully erect penis. Measure the length from your pubis (where it starts), without pushing the ruler in, to the tip. For girth, simply wrap a piece of string around it along the shaft where it is thickest - then measure the string. Depending on the study, average length varies from 5.1 inches to about 6 and average girth is 4.8 to 4.9 inches. With such varied data and methods and populations sampled, many put average erect length at 5.5” Just google penis size study and you’ll find quite a few studies have been published. Note - if you push the ruler in (aka the bone-press method) depending on how much body fat you have, you’ll be giving yourself an extra half inch or more. But, be honest, how useful is the length of your penis that’s hidden by fat, except to maybe give yourself an inkling of how long it would almost me if you got your body fat down to that of a professional athlete. So, that said, if you do go into the weeds looking at penis size studies, make sure to note if the test was bone press or not. fYi: mine is 4.5” long (on a good day) and 4.9” girth. Normal girth but short according to virtually any study out there. Micropenis is a medical condition, usually defined by an erect length of 2” or less. Sometimes, but less often defined as 3” or less.