Here is something I came up with when printing supposedly round objects would come out slightly oval.
Take a coin and measure it’s diameter (25.14)
Create an object using like the one below with an interior diameter slightly larger than the coin’s diameter.
Print it on the center of the platform.
If you can put the coin into the center with no gaps or play, then your “X Size” and “Y Size” settings are spot on. If not, adjust them accordingly.
Works great for me!