Nursing Dosage Calculations the Easy Way!

When it comes to doing nursing dosage calculations, or nursing math, the absolute best, easiest and most foolproof way to solve problems is by using dimensional analysis. You may remember this process from your chemistry class.

In this post I will show you how to use dimensional analysis to set up any dosage calculations question so you can score 100% on this crucial exam!

Sample question #1

Your order reads:
In dimensional analysis, you always start with what’s ordered. In this case it’s 650 mg of acetaminophen. You will write this as a fraction, with 650 on top and 1 on the bottom:

Next, you need to know what dosage amounts your medication comes in. This is known as the conversion factor. In the case of Tylenol, we check our blister pack and see that it’s 325 mg per tablet. The next step is to add the conversion factor as a fraction. Since mg is at the top of our first fraction, it will go on the bottom of our next one so that they cancel each other out.
As we move forward into more complicated calculations, it’s important to know when you have all the elements in place. As you cancel out the units, you ultimately want to be left with only the unit you are solving for.

In this case, we want to know how many tablets to give the patient. Everything except for tablets is crossed out, so we know we are ready to do our calculation.

1) Multiply across the top: 650 x 1
2) Then divide across the bottom: ÷ 325.
What answer did you get?

Sample Question #2

Let’s do another one. Your order reads:
For this calculation, let’s assume midazolam comes in 5 mg tablets. Hopefully, you’ve set up your calculation like this:
Next, cross out the units that are the same…in this case it’s mg.

We are now left with X # of tablets to give our 1 patient. Voila! Now,  do your calculation!

OK…you have the hang of that now? That’s a simple calculation with one conversion. What if you have multiple conversions, medications dosed by weight or even medications dosed by weight AND time? My course Confident Calculations teaches you how to perform all types of medication math with 100% accuracy. Every. Single. Time.

Now, what about math anxiety?

While it may seem like you are the only person in the world with math anxiety, I promise that’s not the case. In fact, studies show that even high math performers can have math anxiety! This horrible feeling related to math performance stems from having negative math experiences that often start at an early age.

The key to reducing or even beating math anxiety is a process that involves replacing negative math experiences with positive ones. And it all starts with my free intro guide to conquering dosage calculations. 

What’s in this free guide?

This FREE GUIDE includes common unit conversions, the basics of dimensional analysis, and ten practice questions. Grab yours here.

The information, including but not limited to, audio, video, text, and graphics contained on this website are for educational purposes only. No content on this website is intended to guide nursing practice and does not supersede any individual healthcare provider’s scope of practice or any nursing school curriculum. Additionally, no content on this website is intended to be a substitute for professional medical advice, diagnosis or treatment.

Last Updated on November 5, 2024 by Maureen Osuna, MSN, RN