How can I check if my 20W Apple adapter is real or fake?

Even I could purchase a fake adapter and print a label that is an exact copy of a legitimate label and sell it. You will find nothing on a label or box that will be able to prove legitimacy. With the counterfeit market for Apple devices/accessories being so huge, it would make no sense to purchase from any third party location. That would be a risky move, and you would have to be comfortable with the fact that your purchase may be fake.

Sorry, but there is no way to determine the validity of a product from a label. If someone has gone to the trouble of designing and building a fake product, surely they can create a fake label or box.

Having said that, what are the concerns you have with the box/label?

Hamzabenalip wrote:

The fact that i never see a box with « made in india,i see only « adaptater made in india »,i bought it for 30$ and i think its legit because all The test seem to be authentic,

If it was purchased from Apple or Authorized Apple Seller, then it is legit. If purchased from a third party, then you just won't know and there is no test, serial number check, or package comparison that will be able to show that it is an authentic Apple product.

Apple has manufacturing facilities in many countries, including India, China, Vietnam.

+1