QuestionHow do you measure your testicles?
Doctors use an orchidometer, which is nothing more than a string of oval beads of various sizes. With one hand they feel the size of your testicle (usually while they are also testing for hernias and retracting testicles -- when they tell you to turn your head and cough). With the other hand they feel the beads on the orchidometer in their pocket. The one that feels to be about the same size is then noted on your chart.
Since we don't have access to an orchidometer, the next best thing is to see a chart of sizes that are drawn to scale. That is what is presented in the Tanner Stage Calculator for Boys. Since everyone's monitor render images at different sizes, there is a scale at the bottom. It should measure 1 inch or 2.5 centimeters. If the image doesn't match the correct size, you'll have to make some adjustments in your head.
One of the interesting things most people can do is put something between their fingers in one hand and they can open or close their fingers in the other hand to be roughly the same distance apart. Precision is not essential anyway for this measurement. So take on hand and feel the width of your testicle and with your other hand find the image that comes the closest to being about the same size. Then note the volume number under the image. That is roughly your testicle size.
To relate the size of your testicle to the Tanner stage of development: