Your curiosity might ask why almost all capsules on the market are similar in shape, well, this is due to easily use and historical reasons. Many people have a misunderstanding that oval shape is easy to swallow, however, the capsule size is the key factor that influence the swallow.
Back to the early period, the capsule was made into oval shape because the capsule was formed by the condensation of liquid, since the early process was imperfect, only the surface curvature formed by the liquid tension could be made. As the oval shape capsules were widely produced and used in the market, some conventional standards have been formed, such as the size of the capsule, the volume of the filling, etc. When it comes to the invention of the automatic capsule filling machine, people realized it was too late to change the capsule shape, even they could make square capsules, they couldn’t change the capsule production line that already has a complete set of standard process controls. Although the round capsule has many problems, the space utilization rate is relatively low, and it will naturally roll elsewhere due to shape, but these are minor problems compared to changing the production line and industry. Just like the of the QWERT button in the keyboard, the shape of the capsule continues day.