Vanity height by sink type — why a vessel cabinet ships shorter

What this diagram shows

A side elevation comparing three bathroom vanities whose finished sink rims all land in the same 34-to-36-inch comfort band above the floor, even though the cabinets are different heights. A drop-in or undermount sink sits on a standard 34½-inch cabinet that, with a ¾-inch top, puts the rim in the comfort band. A vessel sink bowl sits on top and adds 4 to 6 inches, so its cabinet ships about 30 inches — shorter — to keep the rim in the same band. An ADA lavatory caps the finished rim at 34 inches above the floor per ICC A117.1 and leaves open knee and toe clearance with the supply and drain pipes insulated. This is why the calculator sets cabinet height from the sink type.