In the United States customary system, 1 cup is equal to 48 US teaspoons. So, 1/3 cup would be:
1/3 cup * 48 US teaspoons/cup = 16 US teaspoons
Since 1 US teaspoon is approximately 4.92892 milliliters, to convert 16 US teaspoons to milliliters:
16 US teaspoons * 4.92892 milliliters/US teaspoon ≈ 78.86272 milliliters
Therefore, 1/3 cup is approximately equal to 78.86 milliliters.