Why would I need 2 for this area? There is an entire 2nd slab for the island.

what are these measurements, including overhangs

You need to discuss this with your fabricator. They will be able to tell you where they feel the seam needs to be and if there is more than one choice. While you can (and should) approve the final layout including the pattern matching at the seams, most fabricators will have a firm opinion on where the seams should be based on their experience, the layout of the counter and the material itself. They can also tell you if you would need another slab to get a good pattern match at the seam.

Agree - your fabricator should be able to advise best placement for seam(s) based on material and the directional movement in your slab. As mentioned, this may mean the need to purchase more than one slab for pattern match. Absolutely make sure you sign off on the template before any cuts are made.

I promise I intend to talk in detail with my fabricator. But this project is still a month out so I’m just trying to prepare. I have had 3 people come out and measure and bid and no one has mentioned needing a 3rd slab (I already have 2, one for the island and 1 for this area). It would surprise me in a really bad way if I all the sudden needed an entire 3rd slab. When I do the math, I feel like much of this is going to waste as it is.

To answer SashaDog’s question on the dimensions... red line is 54” and blue line is 102”. Slab is 122x70.

Were I a fabricator, I would place seams. If there were alternatives that were even, I'd let the customer pick.

We have an apron sink, so a bit different than your cooktop, but this is where our fabricators put our seams. I am grateful every day that we don't have a mitered corner on our stone. What you're looking at is a separate piece for the deck behind the sink and a small splash for behind the sink under the window.

Theresen, very helpful and definitely making want to avoid the longer seam at the diagonal if I can. Seeing yours mapped out helps. I really think it can be done with the slab I have.

Thanks, I don’t agree with you but we will see what happens.

Here is how it works out in my mind, not totally to scale but not far off either.

I would defer to the fabricator’s expertise. They do this for a living and know best how to layout your counters for optimal stone use and piecing. You can ask to be given final approval before cutting. They will lay it out and you can decide if you want to shift a bit here & there to capture certain features of the stone, etc. If they tell you having seams around the cooktop won’t work, you can ask why, but trust them. Get referrals so you know who you’re dealing with. Tilesetters and cabinetmakers are great resources.