A 1/3 cup of liquid is equal to approximately 2.7 ounces. Converting measurements from cups to ounces can be tricky, but it is important to know in order to ensure accurate measurements when cooking or baking. It is important to remember that the weight of a cup of liquid will vary depending on what the liquid is. For instance, a cup of water will weigh more than a cup of oil. Therefore, when converting these measurements, it is important to keep this in mind.