A teaspoon holds 0.1667 fluid ounces or 4.929 milliliters. Other equivalents are 1.333 fluid drams, 80 minims and 4.929 cubic centimeters. It is also one-third of a tablespoon. This is the standardized measure of a teaspoon as used by cooks.
An actual teaspoon is a small spoon used for drinks or desserts, according to Dictionary.com. The shape and size varies among flatware patterns. For critical measurements, such as medications, ordinary teaspoons should not be used, the U.K. National Health Service points out. A study measured a small variety of teaspoons, finding that they varied from 2.5 to 7.3 milliliters. The average spoon held a bit less than the standard measure at 4.8 milliliters.