You need a minimum clearance of 36" for each walkway; 42" is preferred, 48" if there are multiple cooks in the kitchen. If you want seating on the island, you need an overhang of 12" at a minimum, 15" is more comfortable. With seating, you need a minimum of 42" clearance for a walkway behind the seating. Also, take into account that your counters will have a 1.5" overhang from your cabinet size.
(Pros, have I got this right? I've been learning!)
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