Solved Problem printing circles? (might have solved myself)

so I have printed many things now, but I notice my circular shapes tend to be off. For example, I print a 25x25x25mm cube, its spot on, but to print a 1.25 inch cylinder with a hole in the center, one side of it is oblong, and the hole is not a perfect circle either? Any tips on dealing with this kind of problem??

 

I may have solved my own issue, removed the bed, and noticed the y belt was extremely loose... will update asap

 

i think that was it, I also printed another tensioner for the x axis, because I didnt want to snip off the zip ties and deal with that. Belt tension is key!