Metric Measurements for Volume and Weight

TO OUNCES: Drop the last digit from the number of millilitres (mL) or grams (g) and divide by 3. For example, 156 mL is about 5 oz (15 divided by 3 equals 5).

TO MILLILITRES OR GRAMS: Multiply the number of ounces by 30. For example, 1 ounce is about 30 mL or grams.