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PTCB Conversions l Pharmacy Tech Math!

Mar 17th, 2020
math conversions

PTCB Conversions

Pharmacy technician math gets much easier once you know conversions. It takes some time but, with enough effort, conversions can become a lifesaver for many pharmacy technician calculation questions on the PTCB exam.

Nor do you need to be strong on math, either.

All it requires is simple memorization. There are 10 must-know conversions that you need to commit to memory:

  1. 1 kilogram = 1,000 grams
  2. 1 kilogram = 2.2 pounds
  3. 1 liter = 1,000 milliliters
  4. 1 gram = 1,000 milligrams
  5. 1 milligram = 1,000 micrograms
  6. 1 grain = 64.8 milligrams
  7. 1 ounce = 28.35 grams
  8. 1 teaspoon = 5 milliliters
  9. 1 tablespoon = 15 milliliters
  10. 1 pound = 454 grams

All these conversions are, at some point, going to turn up on the day of your exam.

What you need to do is learn them. There are no simple techniques or methods easier. You just need to sit down and commit these values to memory. One of the best ways is to create flashcards. On one side of the card, put one value and on the opposite side, put the second value. Keep flicking through these flashcards and, in no time, you will have learned these conversions.

Once you have committed these values to memory, you need to know how to use them in pharmacy technician calculations.

Conversion Calculations

Here are some sample PTCB questions; the style and difficulty of which you can expect on the day of your exam.

With the 10 conversions now committed to memory, try to work on these problems and see how many you get correct.

  • Q1. How many kilograms are there in 3,450 grams?
  • Q2. How many micrograms are there in 459 grams?
  • Q3. How many grams are there in 7 pounds?
  • Q4. How many tablespoons are there in 105 milliliters?  
  • Q5. How many grains are there in 325 milligrams?
  • Q6. If I have 4 ounces and 1.4 kilograms, how many grams do I have in total (rounded to nearest whole number)?
  • Q7. Convert 4 teaspoons and 8 tablespoons to liters.
  • Q8. How many micrograms are there in 2.2 pounds?
  • Q9. How many ounces are there in 3,000 grams (rounded to the nearest whole number)?
  • Q10. Approximately how many grains are there in 1 pound?

Get a pen and paper out and start working on these ten problems.

It is far easier, and far more beneficial, to try and work out problems before reading the solutions. It gives added insight into where and why you’re going wrong.


Let’s work through each of the above 10 pharmacy technician math problems and see how many you scored correctly.


There are 1,000 grams in 1 kilogram.

Therefore, we need to divide 3,450 grams by 1,000 to give us the value in kilograms.

3,450 / 1,000 = 3.45 kilograms.


There are 1,000 micrograms in 1 milligram; and 1,000 milligrams in 1 gram.

Therefore, to convert 459 grams to micrograms, we simply need to multiply by 1,000,000 (1,000 x 1,000).

459 x 1,000,000 = 459,000,000 micrograms.


There are 454 grams in 1 pound, meaning 7 pounds is the same as 3,178 grams.


One tablespoon is the same as 15 milliliters.

Therefore, 105 milliliters is the same as 7 tablespoons.


One grain is the same as 64.8 milligrams.

Therefore, 325 milligrams / 64.8 milligrams = 5 grains.


First, we need to convert both values to grams, and then add both values together.

One ounce is the same as 28.35 grams, so 4 ounces is the same as 113.4 grams.

There are 1,000 grams in 1 kilogram, so 1.4kg is the same as 1,400 grams.

In total, then, there are 1,400g + 113.4g = 1,513.4 grams in total. As we are asked to round to the nearest whole number, the answer is 1,513 grams.


One teaspoon is the same as 5mL, meaning that 4 teaspoons = 20mL

One tablespoon is the same as 15mL, meaning that 8 tablespoons = 120mL

In total, then, we have 140mL.

However, the question asks us to answer in liters.

Therefore, we need to divide 140mL / 1,000 = 0.14 liters.


2.2 pounds is the same as 1 kilogram.

1 kilogram = 1,000 grams = 1,000,000 milligrams = 1,000,000,000 micrograms

In each case, we multiply by 1,000 – first grams, then milligrams, then micrograms.


There are 28.35 grams in 1 ounce.

Therefore, 3,000 grams / 28.35 grams = 105.8, or 106 ounces when rounded up to the nearest whole number.


1 pound is the same as 454 grams, or 454,000 milligrams.

1 grain is the same as 64.8 milligrams.

Therefore, we need to divide the number of milligrams in 1 pound by the number of milligrams in 1 grain, to give us the final answer in grains.

454,000 / 64.8 = 7,006 grains in 1 pound, when rounded to the nearest whole number.

Final Thoughts

Did you manage to score all 10 correct?

If not, don’t worry. If anything, this test reveals where your strengths and weaknesses lie and where you need to focus your forthcoming study.

Conversions are an important part of the PTCB math exam. You need to know the above 10 conversions and be able to apply them in a variety of different situations. These are some of the must-know details you need to know. Get it right and these can become guaranteed correct answers.

Found this guide to PTCB conversions helpful? Check back to our blog soon for even more exclusive content to help you succeed at the PTCB examination.

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PTCB Test Prep Author


Elaine Walker

Elaine joined PTCB Test Prep in 2017, currently serving as the lead product development manager overseeing both course development and quality improvement. Mrs. Walker is a graduate of California State University and has worked as a pharmacy technician for over twenty years – with particular interests in pediatric pharmacy, extemporaneous compounding, and hospital pharmacy. Over the past 8-years, she has helped prepare thousands of students for the PTCB examination.