One serving of olives typically contains between 10 and 20 olives, depending on the size of the olives and how they are served. Olives vary in size, with smaller varieties like kalamata and manzanilla olives only containing around 5-7 olives per serving. Meanwhile, larger varieties such as Cerignola or Kalamata can contain up to 20 or more olives per serving. Generally speaking, one should expect around 10-20 olives per serving of any variety of olive.