For length, if you want a full sized 33" sink, then thats 24" for a DW, a 36" sink base, and at least 18" on the other side for a trash pullout. Now, if you want your prep zone beside the sink because you don't have a prep sink, then that's 36" to one side of the sink. The rule for combining zones is that you take the large dimension for the the double zone and then add 12" That means that you'd need 48" on the prep side of the sink if that's the only sink in the kitchen. So, 24" for the DW, then 36" for the sink, and 48" for the prep zone. That's your 9' island.

Now for depth. You want at least 9" of clearance on the other side of your cleanup zone for safety's sake. That could be a (useless) 9" overhang or 9" bookshelves on the other side. But if you're using stock cabinets, the easiest thing is to use a 12" deep wall cabinet on a built up base on the other side. That gives you 36" in depth.

Add in countertop overhangs of course.

Thank you so much! Need to relocate the frig so I can get the 9 foot length-with the angles currently in the island, length is 8 feet and it feels cramped. Hope to download a floor plan app soon....