What should be the standard size of 42 euros written on the Nike shoe box?

According to Nike's shoe size standard, EUR 42, that is, European size 42, 8.5 refers to American size.

42 Euro = 8.5 USD (US 8.5)= 7.5 GBP (uk 7.5) = 26.5 cm.

The specific criteria are as follows:

Extended data:

The size of shoes, also known as shoe size, is generally marked in the following ways: international, European, American and British. The international standard shoe size indicates the millimeter of foot length. The China standard measures the size of shoes in millimeters or centimeters. For example, 123 means in millimeters and 12.3 means in centimeters. In fact, the two references are the same.