Sink Hole Sizing for Faucets
Sinks have different holes pre-drilled for various types of faucets. When you buy a sink, match the hole size to the faucet you intend to install. If it is a single-hole faucet, choose a single-hole sink--one with a single hole drilled in the center. If the faucet is a standard center-set faucet, one with a center-set faucet hole is required. On a wide-spread faucet, a set of wide-spread mounting holes is required to properly mount the fixture. The sink mounting holes must line up with the faucet mounting holes. You can drill your own holes in a sink with a hole saw sized to fit the faucet. Or, drill the holes into the counter top, depending on the size of the sink.
Sink Mounting Holes
Sinks mount in your counter, so when you install the sink you must cut a hole into the counter. The size of the hole depends on the sink's dimensions. The standard sink is 22 by 30 inches with a basin that is 8 inches deep. The hole cut into the sink corresponds to these dimensions. The standard sink has a rim around the basin. This rim is about 2 inches wide and it rests on the counter when the sink installs inside it. The hole is therefore cut smaller than the overall width and length of the sink's rim, to allow it to hold the sink in place. This is not true of all sinks, however.
Undermount sinks install underneath the counter top. They have a rim around the top that is about 1 inch wide, however the rim is not exposed and does not sit on top of the counter. Cutting a hole for an undermount sink requires more precision and a finished edge, as the edges of the sink hole are visible. The hole size for the sink is the exact same size as the sink basin in this installation. Faucet hole sizes remain the same but the faucet mounting holes are cut into the counter, not the sink.
Apron Kitchen Sinks
An apron kitchen sink is an undermount sink with the front side of the basin exposed. This sink hole is cut in the front half of the counter top. It is the same size as the basin but the cut runs right up to the edge of the counter top. In essence, the sink hole is more of a gap cut into the counter top. Since this is an undermount sink, the cut requires a precise, finished edge and is usually made with a router. Faucet holes are cut into the counter top and not through the sink itself.