Mini Kelly sizing real talk

Looking to have a custom Kelly made and I'm debating a mini Kelly or a larger one. I typically go for smaller bags but I did just get a Kelly en Disordre which is 20cm but that is for the very specialist of occasions. I'm wondering how mini the mini actually is. I don't want to not be able to fit my iPhone, keys and a slim wallet in it.

Any advice from you experts would be welcome