I'm trying to find out how big a slab of granite is so that I can figure out my counters and island.
It depends on the size of the block from which the slab was sawn and this varies.
Engineered stone slabs are 54" x 120" +_.
I suggest you connect with a fabricator who has a Slabsmith or similar program. This lays out your tops on the slabs in stock and you can grain match.
Thank you!! Just wanted to make sure I don't have seams on my island which looks like will be around 9-10'x4'.
You can't be sure that a particular granite you want will come in a big enough slab. You'll have to keep an open mind and visit a stone yard to find one you like that is big enough.
FWIW, we are getting Ceasarstone (had granite before, and just decided we wanted a different look), and designed the island's size based on the size of the slab (I ended up with 2 35" drawer stacks, a 4-1/2" filler for power, 24" microwave cabinet, 18" drawer stack, 3/4" panels on each end), which although nominally 120" really only allows for an island of 118" (plus 3/4" on each end, plus a little tolerance). I guess they need a little tolerance for making the edges.