Quirby's custom Kirby sprites, NEED CHECKING

[Quirby64]

I don't know much about GIMP, but don't you have a circle tool in that program, too? If so, I think you can make perfect circles the same way by dragging and holding down the shift key. To be perfectly honest, this kind of stuff is standard for nearly every drawing application out there.

Also, why do you want to make perfect circles all the time? There are some times that a slightly deformed circle look a little more interesting than a perfect one. Just try your options and stick with what looks best to you.

there's nothing in GIMP for circles, but you can select a area in the shape of a circle.