First of all, I want to make clear that I don´t know how to calculate the gravity of a planet in m / s². Starting from there, I don´t know any formula referring to this knowledge and that is why I am doing this topic.
My question is, what would be the size of an earth-like planet to have a fifth of the Earth's gravity? I know that aspects such as density and size influence, but my knowledge of the subject is so poor that i couldnt calculate something like this by myself. I would be grateful to anyone who could give me an answer on this topic.