I want to get an unfinished wood vent cover that will go in the toe kick in my new bathroom. I'll stain it to match the gray cabinets. My contractor said the vent has a 3"x10" opening and the toe kick is 4.5" high.

My choices are:

3"x10" opening with 4.5" x 11 3/16" overall size

2.25" x 10" opening with 3.75" x 11 3/16" overall size

I like the idea of having a little room around the vent cover, but I have no experience to know if I'm noticeably limiting air flow by going with the smaller size.

And I've seen lots of advice that I won't notice the toe kick after a while, but it's directly in my line of vision as I enter my bedroom - so I know it's a detail that I will see.

Thank you