Nursing is all about applying what you know to effectively promote health, prevent illness, and compassionately care for the ill and dying. Although the NCLEX rarely offers up any knowledge-based questions, studying for your boards or nursing school exams invariably means a lot of memorization; after all, you need to learn the knowledge to apply it.

One area where this is especially true is when it comes to lab values. If you know what’s normal, you can easily determine what’s not, so we’ve put together some ways to help memorize some common values.

Complete Blood Count (CBC)

White Blood Count (WBC)

The percentages in WBC that make up the whole count vary a little, but as an aid to memorizing them, stick with just ‘average’ numbers.

Never Let Monkeys Eat Bananas

60, 30, 6, 3, 1

Neutrophils: 60% (range: 55-70% or 2.5-8.0 x10⁹/L SI units)

Lymphocytes 30% (range: 20-40% or 1.0-4.0 x10⁹/L SI units)

Monocytes 6% (range: 2-8% or 0.1-0.7 x10⁹/L SI units)

Eosinophils 3% (range: 1-4% or 0.0-0.5 x10⁹/L SI units)

Basophils 1% (range: 0.5-1% 0.02-0.05 x10⁹/L SI units)


Red Blood Cells (RBC), Hemoglobin and Hematocrit

There are about 5 (million) RBCs (4.2-6.1 million)

Multiply the RBCs by 3 to estimate normal Hemoglobin (Hb) = 15 g/dL or multiply the RBCs by 25 to find the SI units = 125 mmol/L

Hemoglobin for men is 14-18 g/dL (140-180 mmol/L) and women is 12-16 g/dL (120-160 mmol/L)

Multiply the Hb by 3 for the hematocrit = 45% (If you know an easy way to memorize volume fraction, let us know!)

Hematocrit for men is 42-52% (0.42-0.52 volume fraction) and women is 37–47% (0.37-0.47 volume fraction)

A general rule of thumb is that Hematocrit is three times the Hemoglobin (in US values).


Metabolic Panel

Creatinine and BUN

Some people say that Creation took 7 days, which is half (0.5) of 14.   0.5 is the number to remember for Creatinine.

Creatinine for women is 0.5 – 1.1 mg/dL (44-97 mcmol/L) and for men is 0.6-1.2 mg/dL (53-106 mcmol/L).

BUN is 10-20  mg/dL, which is about 20 times greater than creatinine for US values (0.5 x 20 = 10).

To estimate BUN in SI values, creatinine values can be divided by (50/5 = 10 or 100/5 = 20).

 Potassium and Magnesium

When it comes to the heart, these two have great influence over each – try to remember the lower range of these values, using the first prime numbers: 1,3 and 5.

Magnesium (Mg): 1.3 mEq/L

Potassium (K): 3.5 mEq/L

35s and 45s

When you are memorizing lab values, you might notice plenty of 35s and 45s. Use this chart to see how they line up.



We have tried to make these work for Canadian lab values as well, but not all of them work. Let us know if you have any mnemonics that are useful for learning lab values in the units common in Canada!

Feature Image Attribution:

Wikimedia Commons, USMC file USMC-110316-M-OU013-002, no author listed, [Public domain], via Wikimedia Commons


Posted by Benjamin O'Connor


  1. You are amazing!! Thank you for helping nurses to the best we can be!


    1. Catherine MSN RN July 13, 2018 at 3:20 pm

      Thank you, Myrna!!! Glad to be here for you!


  2. […] internet and NCLEX study guides are full of tips and tricks for learning your normal lab values. Whatever method you choose, you’ll have a huge advantage if you memorize your labs (and what […]


  3. God bless you. You are great


  4. Super helpful


  5. Donna M Grant July 1, 2019 at 6:56 am

    Thanks I wish I knew this earlier in nursing school


  6. Mathias de Hohenzollern January 4, 2020 at 10:21 pm

    I belong to the 1st batch of NCLEX-RN CAT takers way back in 1994 and I do remember I passed it with just a minimum # of 75 test questions.
    I was just lucky I guess as I was very poor in memorization and math computations but I was able to practice safe RN skills in my 25 years of service here in the 🇺🇸 as a foreign-graduate BSN and now as a retiree, I can look back proudly that I did good at a time when I least expected it to be.


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