DPI converter

Hi im not sure if im posting in the correct forum but it seemed appropriate

I am curentley helping my misses set up a portfolio for university and i need to change the images DPI to 72 and i was wondering if any one can suggest a free image converter in wich i can do this

Any help would be greatly appriciated

GIMP can i think.

Photoshop too. There’s a probably a free trial if you don’t want to purchase it.