Pistachios are divided into various types, and each type comes in different sizes. The common types of pistachios include the following: Akbari Pistachio: One of the largest and highest-quality types of pistachios. Common sizes: 18-20, 20-22, 22-24 Ahmad Aghaei Pistachio: It has a mild taste and an elongated shape. Common sizes: 22-24, 24-26, 26-28 Kalleh Ghouchi Pistachio: A large, round pistachio with a large kernel. Common sizes: 20-22, 22-24, 24-26 Fandoghi Pistachio: Round and smaller than other types. Common sizes: 28-30, 30-32, 32-34 Badami Pistachio: Almond-shaped and elongated. Common sizes: 26-28, 28-30 These sizes are determined based on the number of pistachios per ounce (approximately 28 grams); the smaller the number, the larger the pistachio.