Final answer:
Optimal countertop space next to the sink should range from 8 diameters side-to-side to 15 diameters deep to ensure functionality for food prep and cleaning.
Step-by-step explanation:
When designing a kitchen, it's important to consider the counter space needed for functionality and ease of use. Traditionally, an older "rule of thumb" recommends that there should be around 5 diameters of the sink side-to-side and 7-8 diameters deep of counter space on at least one side of the sink. However, newer work suggests that the optimal countertop space might be as much as 8 diameters side-to-side and 15 diameters deep. This ensures that there is adequate space for food preparation, cleaning and other kitchen tasks without hindrance, taking into account that the bottom few inches of the walls of the inside of the basin are not completely covered.