Dosage Calculation Review

Calculating the correct dose of medications for patients is an essential part of a nurse’s job, so learning dosage calculations is a must for all nursing students. Medication errors can be detrimental to a patient, which is why appropriate medication administration is so important. While your nursing school should have required you to take a dosage and calculations course, you may want a review to ensure you’re ready for the registered nurse licensure exam, or NCLEX. Aceso’s review provides directions for performing some of the most common types of dosage calculations.

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Basics of Dosage Calculations

Calculating dosages starts with some very basic steps. Reading a medication label and understanding how many milliliters or how many tablets are required in a dose ordered are key. Understanding a basic doctor’s order, metric units and volume units and simple nursing math are necessary in medication dosages. You’ll begin by working out basic metric conversions and work up to solving more complicated dosage calculations.

Types of Medication Dosage Calculation Methods

It’s common for some nursing and other medical professionals to use a calculator to calculate drug dosages. However, calculators may help decrease medication errors due to issues with mathematical calculations, but they won’t help recognize a conceptual error. There are three primary dosage calculation methods to accurately figure the appropriate amount of medications.

Ratio and Proportion Method

This is one of the oldest methods used in drug calculations. It gives you the ability to compare units of measurement, numbers or values. To figure doses, you’ll use a process of multiplication and division to work through the problem.

Dimensional Analysis Method

Dimensional analysis is helpful in calculating weight-based dosing and complex continuous intravenous (IV) infusion time and flow rates. To easily solve these dosing problems, you must be familiar with the metric system, which replaced the classic apothecary system. Keep a copy of the metric conversions handy until you know them well.

Formula Method

The formula method uses an equation to solve for an unknown quantity, similar to ratio proportion. Dosage calculations require the use of a conversion factor, such as when you’re converting from pounds to kilograms or liters or when you need to know how many ml (milliliters) are in a fl oz (fluid ounce). The formula method is simple and lets you work with various units of measurement and converting factors to find the desired dose.

Tips for Preparing for NCLEX Dosage Calculation Questions

Practice questions are great preparation for answering questions on the NCLEX. Fill-in-the-blank questions are commonly used for IV flow rate, drug calculations and figuring the intake/output of a patient. You’re expected to have the knowledge to perform these calculations and put the correct answer in the blank provided. Always include the decimal point and follow the directions provided on the computer screen, including any examples and the unit of measure for your final answer. There’s an on-screen calculator you can use to calculate an answer.

Calculating correct dosages using various methods is a skill nurses use every day, so it’s important you have a solid understanding of this nursing concept. Master the skill with Aceso’s Dosage Calculation Review. Contact us at 321-230-5054 to enroll in the next available class.


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