Measure the cabinet size under the existing sink or where the new sink will go. Measure from gable to gable (left to right). See diagram. Be sure to measure from outside edge to outside edge. To save time, double check your measurements. This is the "Minimum Cabinet Size", and this size is noted next to each sink model in the BLANCO catalogue. Standard kitchen cabinets come in size increments of 3" (for example: 18", 21", 24", 27", 30", 33", 36" etc.).