Granite Vanity Top Sizes With Sink: What to Send Before the Cutout Is Cut
Granite vanity top sizes with sink are not set by the basin's outside diameter. They come off the sink maker's cutout drawing, plus the finished top dimensions and the sink type. This guide covers how undermount, drop-in and flush-set change the hole, how depth and overhang come back off the cabinet, what a 30 mm top does after cutting, and how many tops a 20ft container carries at 346 m2.
Granite vanity top sizes with sink — what do I have to send before you cut?
Three things: the finished top dimensions, the sink type, and the sink maker's cutout drawing. Miss one and the shop is guessing, and the guess usually lands as a hole off centre or a cutout one size too big. Send finished dimensions, not the rough opening in the cabinet. The sink type decides which edge laps over which. The cutout drawing gives the hole outline and the datum it is measured from — it is not the sink's outside profile. Put the quantity in the same email so the top area can be priced. Pink Hemp G564 is normally run for stair treads and cladding, with 30 mm polished slabs in stock; state vanity use on the order and it is scheduled on the vanity-top line.
Undermount, drop-in or flush-set — where does the cutout actually differ?
It differs in which way the rim laps the stone. An undermount is fixed from below, so the cutout runs smaller than the outer rim and the rim grabs the stone from underneath: the surface stays unbroken and wipes clean. A drop-in sits on top, so the cutout runs larger than the bowl and smaller than the outer rim, and a bead of sealant under the rim does the water work. A flush-set needs a rabbet machined around the hole, cut to the rim thickness so the rim lands level with the stone. Each fails in its own direction: undermounts when the hole is too big, drop-ins when it is too small, flush-set when the rabbet is not a consistent depth.
| Sink type | Hole vs. rim | What gets machined | Usual failure |
|---|---|---|---|
| Undermount | Hole smaller than outer rim; rim grabs from below | Polish the cutout face, flatten the bond face | Hole cut oversize, rim cannot cover, open joint |
| Drop-in | Hole larger than bowl, smaller than outer rim | Ease the top edge of the cutout | Hole cut undersize, sink will not seat |
| Flush-set | Rabbet around the hole, depth set by rim thickness | Flatten the rabbet floor, clean out the corners | Uneven rabbet, rim sits high on one side |
Why can't the fabricator work from the sink's outside diameter?
Because the outside diameter is not the cutout line. It measures the widest point of the rim, while the cutout has to sit inside that on an undermount, or between the bowl and the rim on a drop-in — two different numbers by definition. Flush-set is further off again, because what matters is the inner profile of the rabbet. The second trap is taper: on a tapered basin the rim profile and the base profile are not the same size, so a tape run around the bottom of the sink will not match the drawing. The reliable sequence is this: get the sink maker's cutout drawing with the hole outline and its datum; if you cannot get one, ship the actual basin to the shop and have the hole fitted to it. A cutout is not a reworkable operation: get it wrong and the top is scrap. Never describe it as 'about' anything. Even with the drawing in hand, print the hole outline at 1:1, lay it over the basin and check the fit before the saw goes in.
Depth, overhang, backsplash and faucet holes — can they all go on one drawing?
They have to. Depth is not a number you pick first; it comes back off the cabinet. Measure from the cabinet face to the wall — not the old top — add the front overhang you want, then allow for the gap at the wall; that total is the depth. Say the cabinet is 550 mm deep, you want 20 mm of overhang and 10 mm at the wall: the top comes out at 580 mm. Those three figures are an example only; use your own cabinet and your own overhang. The backsplash eats a strip along the back edge, and once it is on, the clear distance from cutout centre to back edge changes, so its height and thickness belong on the same drawing. Same for the faucet, soap dispenser and drain: one plan, one datum edge (back edge or left end), every position as a centre distance, never as a running total. On an undermount the drain is set by the basin; the faucet hole sits on the basin centreline and still needs clear space between the faucet base and the inside face of the backsplash; too little and the faucet body fouls the backsplash before it seats.
Is a 30 mm top still strong enough once the hole is cut?
What matters is how much stone is left between the cutout and the edge, not the nominal thickness. 30 mm is the slab thickness for Pink Hemp G564; after cutting you are left with four borders. The narrower they get, the more a leaned-on edge or a basin full of water concentrates stress at the cutout corners. Three things help: radius the cutout corners instead of leaving them square; carry an undermount on a bracket or subtop so the basin's weight goes into the frame and not into the adhesive; ease the cutout face to take out micro-cracks at the hole edge. Weight belongs in the same decision — a 30 mm slab runs 81 kg per m2, and a 1200 x 600 mm top is 0.72 m2, about 7.75 sq ft, at roughly 58 kg: two people can carry it, one cannot. Size the crate and the site crew to that number.
How many tops fit in a 20ft container?
Divide the area: 346 m2 divided by area per top. At 1200 x 600 mm, 0.72 m2, that is 346 / 0.72 = about 480 tops. That is the area sum only. 346 m2 at 81 kg per m2 comes to about 28 t; check that total against the carrier's payload limit — heavy cargo usually tops out on weight before volume. Tops also travel in timber crates, and crates take space, so the real count lands under 480. When you ask for a loading figure, give three things rather than a set count: size per top, thickness, and whether crates are needed. Minimum order is 100 m2, which at 0.72 m2 per top is about 139 tops. Stock slabs ship in 5 days; cutting and edge polishing are separate operations, so the earlier the drawing is signed off, the earlier the job is scheduled.