How to Do a Dosage Ratio & Proportion Calculation Online

Doctors, nurses and pharmacists use dosage ratio and proportion in the preparation and administration of medications. A ratio describes one number as compared to another. A proportion is an equation that involves two ratios. Ratio and proportion in terms of dosage determines how much of a medication a person needs to receive the dosage strength that is ordered by the physician. One way to make this calculation simpler is to use an online dosage ration and proportion calculator.

Instructions

Solids

• 1

  Go to an online dosage calculator at manuelsweb.com/nrs_calculators.htm and click on PO dosage calculator -- solids.

• 2

  Click on the drop-down menu next to "Form of medication" and choose the appropriate form. The choices include Tablet, Capsule, Caplet, Lozenge, Troche, Suppository, Patch.

• 3

  Enter the numerical portion of the dosage ordered by the physician in the box next to "Dose ordered." For instance, you might enter "100" if the dosage is 100 mg.

• 4

  Enter the numerical portion of the dose contained in one tablet in the box next to "Dose available per tablet." For example, you might enter "50" for 50 mg.

• 5

  Click "Solve" to view the answer. You will see the numerical portion of the dosage as the quotient of the dose ordered divided by the dose available. In this example, the calculator would divide 100 by 50 to get the answer, "Give 2 tablets."

Liquids

• 6

  Type in the numerical portion of the dose ordered in the box next to "dose ordered." For example, you might enter "200" for 200 mg.

• 7

  Enter the numerical portion of the concentration of the dose in the box next to "dose available." For instance, a liquid medication might contain 50 mg per mL. In this case, you would enter "50" in this box.

• 8

  Enter the numerical portion of the amount of liquid related to the concentration. Using the previous example of 50 mg per mL, you would enter "1" for 1 mL of medicine.

• 9

  Click "Solve" to view the amount of medication to administer. In this case, the calculator would divide 200 by 50 and multiply the quotient times 1 to get the answer "4." In other words, you would administer four applications of a 1 mL dosage.