Question on bathroom vanities/cabinets

You want your finished height at 32 inches. So if you have a 1 inch thick top then the vanity cabinet needs to be 31 inches.

This is not written in stone. There is nothing wrong with what is called comfort height vanities which are a full 36 inches high, same as your kitchen cabinets. I would stick with the shorter ones though if you have small children who are going to be using it.

Welcome jaearhart. Dave gave some great advice when he said it isn't written in stone. Most tradesman would have just spit out the 32" finished height cookie-cutter factoid and not followed up with the common sense but oft ommited option of a custom height consideration.
For me 32" is okay because I am short, but my wife had me add 4" to all our counters because she doesn't like to bend over and all our kids are grown; another thing Dave covered.
Great advice Dave you covered all the bases!

Everyone I've made a bathroom cabinet for in the past couple
of years has asked to make it higher than the std 30"
I was told that the higher ones are showing up in the stores
and it's appearing to be a new trend.
Maybe foot stools for kids will be getting popular again.:laughing:

The common tall cabinet of old was 34 1/2" which is the same as a kitchen cabinet. But some manufacturers in the last couple of years are offerring a 33 1/2" height, which apparently is a better compromise for a wider range of people's heights. Either of these is a tremendous improvement over the old standard 29" cabinets.
As Big Dave said, it's a matter of personal comfort. I have actually built vanity cabs that were 40" high. When the customer is 6'9" you give them what they want:yes: