To determine the size of a set in Python, use the built-in len() function. This returns the number of unique elements in the set, as sets automatically eliminate duplicates.

Example:

my_set = {1, 2, 3, 4}
size = len(my_set)
print(size)  # Output: 4

• For an empty set, len() returns 0:

  empty_set = set()
  print(len(empty_set))  # Output: 0

Note: The term "size" in this context refers to the number of elements, not memory usage. If you need the memory footprint (in bytes), use sys.getsizeof(set) or set.__sizeof__().