In the 3nd intercostal space, on the mammillary line, 4 cun lateral to the anterior midline.
How to locate
First identify the mammillary line by drawing an imaginary line between the clavicular midpoint and nipple. This line is 4 cun lateral to the anterior midline.
Palpate along this line from the top and locate Yingchuang ST-16 in the 3rd intercostal space.