How many users can be added to one group chat?

I can not find any documentation but the median is 20.

Averythomas wrote:

I can not find any documentation but the median is 20.

If you don't know the maximum, you can't know the median.

iCarter wrote:

Is there a maximum, and if so, what?

Apple does not specify a maximum:

Send a group message with your iPhone, iPad, or iPod touch - Apple Support