Medicine dosages are calculated on people's masses or weight. A dose is the amount of medication you take at one time. By contrast, the dosage is how to take the medication as prescribed: a specific amount, number, and frequency of doses over a specific period. In other words, a dose is simply the amount of medication you take at one specific time. The dosage is the dose, or amount of drug, plus when and how often to take it. A dosage guides how you take or give the medication that's been prescribed. Doses are usually measured in metric mass units such as milligrams or milliliters. A small child will receive less than a heavier adult. For a particular medicine the recommended dosage for a child weighing 10 kilograms (approximately 22 pounds) is 50 milliliters of liquid medication per day.