The cabinet size dictates the sink size so what sink do you like if that is the big issue then choose the sink and get the cabinet you need to fit the sink. No one can tell you what you need . I like a 24” single bowl sink but I have 2 back to back in my island. You need to share a bit more info.

is this your main sink? assuming you will center it in the island then? I believe you would need a 36" cabinet for 30"-33" sink. I think 27" is max for 30" cabinet [check specs on the sink you are considering]...

I have a 4x8 island but a prep sink on the island. it is off center towards one side.

It is my main sink. And ideally I’d like the sink no less than 30inches. I was concerned that it would be too big for the island but I don’t think it will be. Then the issue is how big a cabinet does it need because if the sink cabinet goes over 30 inches I will need to reduce elsewhere (likely my wine fridge!).

Go with a larger sink cabinet to fit 30” sink! You will still have plenty of counter space if that’s your concern. My current house has 26” sink for the 30” cabinet which is okay but a bigger sink would be better. Currently building now and putting 30” sink in my island which is similar dimensions to yours

30" won't be too big for the island, but you want it situated so that you have at least 36" prep space to one side, preferably not over the DW--unless you have a prep sink elsewhere. (36" is the minimum recommended by the NKBA). IIRC, Joseph Corlett, a countertop repair pro, has said a 30" sink will fit in a 30" cabinet. You might direct a question to him, or ask the question in the title of a different thread.

If you were the type of person who uses a double bowl sink to wash on one side and dry on the other, for example, then yes, go for a 36" base and a larger sink. If not, I think you'll be fine with a 30" sink base and a single bowl sink if you use a D shaped sink. It will give you ample space to wash and what-not and it will not overpower the island. The D shaped bowl is larger front to back so it gives more room than a traditional rectangle single bowl. Good Luck!

@n129tepper - What size sink did you decide on? I’ll have the same size 8‘x4’ foot island, so I was planning on going with a 30” inch sink. That seems plenty big to me.

Deana I ended up with a 33” inch base cabinet. I haven’t purchased the sink yet but it will be 30”

Thanks so much. do you suggest that because you think 30 will be too small?