Alight year is appropriate for measuring?

A light year is used for measuring distance.

I am pretty sure its not appropriate for measuring because you cant really measure anything with a light year. Bu then again you can use it to measure space. For example, Saturn is exactly 0.0001268 light years away from earth. But its really what you are trying to measure. Like if you were trying to measure how far Japan is from China you would use miles. I hope that this was helpful.