Education and Communications What size are Sonic drinks? How many ounces is a large drink at Sonic? 32 oz How many ounces is a medium drink at Sonic? 20 oz How many Oz is a small at Sonic? 14 oz Related Posts:How to make a mojito without muddling is one of the Muddler alternatives.Great Value Pumpkin Spice Cappuccino Mix is a single serve drink.Is Sonic Generations on Xbox?What is the best dessert at Sonic?