There are 29.574 milliliters in one liquid ounce. Milliliters are a unit of measure in the International System of Units, more commonly known as the metric system.
As of 2014, the United States is the only industrialized country that does not use the metric system as a standard form of measurement. The wine and liquor industries in the United States converted to the metric system following the passage of the Metric Conversion Law in 1975. Other instances in which the metric system has become more common in the United States include the measurement of medications, specifications for cameras and other electronic devices, and nutrition labeling on food.