My interior dimensions measure 12 inches wide x 15.5 inches long x 8 inches deep -- it's a zero radius Ticor, I think having zero radius makes it a big little sink since I can use every inch of it. I wouldn't want it any narrower, for sure. But it's very useful at the size it is. I didn't plan to put a prep sink in, it was a last minute change and I am so happy I did it -- it makes working with two of us in the kitchen a breeze (and fun).

I have a freak issue which centers on the sink having a rear-set drain -- unfortunately the faucet I chose (together with the placement of the faucet) drops water directly onto the forward edge of the drain which causes about 90% of the water to ricochet out of the sink and onto the backsplash when the faucet is facing straight foward and not in "spray" mode. If I catch it early enough when I turn it on, it can be avoided (takes about 2 seconds to begin) -- this is all to say MAKE SURE THE WATER DROPS DOWN THE CENTER OF THE DRAIN and not on the edge.

My sink is the Franke GNX 11016 which measures 15 1/2" x 15 1/2" x 8" and the drain is in the back right hand corner. It is a really good size for being able to put a colander in when draining carrots or grapes, you can fit a pot under for draining pasta easily, and I don't have splash issues because of where the drain is located. That was pure dumb luck as opposed to something I actually considered when choosing sinks.

I would want one big enough to swish greens, like kale, chard etc around in the sink.

I asked this question earlier in the year to make sure I wasn't going to undersize accidently. A few people relied that their prep sinks were about 15-16" wide and that they wouldn't recommend going any smaller. My current sink has a bowl about 19" wide. I put something in the sink to shrink it down to about 15" and went about my meal prep. They were right; don't go any smaller.

My prep sink's interior bowl dimensions are 15-3/4" square and I would not want it any smaller. Occasionally, I wish it were wider...17" or 18". Most of the time, though, it's fine.

I have a Blancoprecis in cafe brown undermount with dimensions of 20 3/4 W, 18 L, and 7 1/2 D. I got a sink grid that I often use to
rinse veggies & fruits. It gets a lot of use.

Thanks so much for all the feedback...good to know so that I don't under size it and create a useless hole in the island!