Feb 07, · Do they use a bendable ruler or a tape measure to compensate for curves? I measure standing with my penis straight out on the top of the shaft, but if I use a ruler and not a tape measure, my stats do change by a bit. I have learned that you measure length from the top of the penis and girth at mid-shaft. But I have seen people suggest and even guys post pics on here where they measure length from the side and girth from the base. Next, measure the girth of the penis (that is, the circumference or thickness): For this step, use a soft measuring tape or a piece of string. If you choose the latter, make sure it doesn't have any stretch.