As a general rule, the sizes of beverage servings depend on the type of drink you purchase. Although serving sizes may differ for select products, most follow these standard guidelines: 8 ounce: Most juice, soda, tea, and kombucha options have 8oz servings available. 1 can: Because sparkling water and diet soda are low-calorie options, the serving size generally includes an entire can. 1 bottle: For sports drinks, the serving size usually includes one bottle. 1 packet: For powdered drink mixes, a serving size typically includes a single packet.