This depends on the style of the fixture.
Standard height for bathroom vanity with vessel sink.
Vessel sinks typically add 5 6 to the height of the vanity countertop.
Since the sink tends to have around 6 on its own you will need to have a total vanity height of 36 so the vanity minus sink will be 30 in size.
But for vessel sinks vanity tops and undermount sinks the standard height ranges from 32 to 36 inches.
The standard bathroom sink height varies from 31 inches to 36 inches.
For pedestal sinks height range starts from 30 to 35 inches.
30 most of the time you will find that a regular bathroom vanity will have to be a bit lower to add the extra vessel sink height.
For homes with disabled.
Generally speaking a bathroom vanity will be lowered in order to accommodate for the extra height added by a vessel sink.
Generally the ideal height for a bathroom vanity with 8 inch high vessel sink is between 24 and 35 inches.
An ideal height for a vanity with an 8 inch tall vessel would be between 24 and 35 inches following nbka standards and based on the height of the occupants of your home.
You can see that the vanity height is 29 6 5 for the vessel sink for a total height of 35 5.
For decades standard bathroom vanity height was 30 to 32 inches but this range may be less common today.