Penis length measurements are divided into length in the flaccid state, and length in the erect state. A straightedge can be used for this measurement. In the flaccid state, the penis can be measured by holding the flaccid penis straight with one hand and pressing the end of the straightedge firmly against the skin at the base of the penis so that the straightedge is parallel to the penis. The straightedge is pressed down as far as possible, not from the root of the penis, but as deep as possible, until the distance from the pubic symphysis, the innermost bone of the skin’s fat, to the opening of the external urethra of the penis. This distance is the length under weakness. The length under erection is when the penis is fully erect without holding it in place with your hand. Again, place a straightedge parallel to the penis and press the ruler down as far as it will go on the pubic symphysis. Then observe the size of the ruler corresponding to the most distal position of the penis, which is the external urethral opening. This distance is the length when erect, which is usually more meaningful when erect. If it is more difficult to operate the measurement by yourself, you can go to a professional hospital to measure under the guidance of a doctor. If patients have any discomfort, they need to consult a doctor for examination and early treatment.