Is it mandatory to shave your head when you do your military service in Switzerland?

I'm very intrigued about this question, especially cause I'm a male.

No.

Yes, both males and females in Switzerland going to the Army on a part-time basis have to shave their head, just like the US marines professional army. Why would you expect anything different?

It's a very intelligent question that you asked.

Official photos:

https://www.vtg.admin.ch/de/die-schw...der-armee.html

and here's a more visibly hairy one:

https://images.app.goo.gl/VjMofser7PZwhJmY9

...and not only are their heads shaved.

No.

The rule in practice is:

Your hair must end above the shirt collar when standing upright and you must be able to do your job like everybody else, and do it safely.

In theory your hair can have any length and any volume. But you must be able to stow it under your cap, the beret if applicable, the helmet. Not sure how that works with the gas mask, seems impossible to get that gastight. A pigtail won't do as the string of hair may get loose and get entangled in a part of your vehicle or other equipment, resulting in severe harm or even death.

In practice people wear hairnets. However that's a major PITA as well as a hygienic issue especially in the summer. And it's rather time-consuming when everybody is short on time, all the time. So virtually everybody cuts their hair short eventually.

ETA:

The legal basis is the Dienstreglement . The relevant paragraph is #58, which translates to:

The uniform is evidence of the membership of the army. Wearers of the uniform represent the army and are required to appear and act appropriately and correctly. In particular, the hair is to be clean and well-kept; long hair must not be worn openly. The hair as well as adornments and piercings must not impede your doing the job or threaten your personal safety. [..]