Nursing Conversions Cheat Sheet for the NCLEX (mcg, mg, g, mL, lb, kg)

Nursing conversions all run on a handful of fixed relationships you memorize once. In the metric system, every step between micrograms, milligrams, grams, and kilograms is a factor of 1000. For body weight, 1 kilogram equals 2.2 pounds. For volume, 1 liter equals 1000 milliliters, and 1 milliliter equals 1 cc. Learn those, always convert everything to a single unit before you calculate, and most NCLEX math collapses into one clean step.

The one chart to memorize

Conversions are the silent prerequisite for every dosage question. If you convert the units wrong, the arithmetic that follows is wrong no matter how carefully you do it. Here is every equivalent the exam expects you to know, in one place.

Metric weight: mcg, mg, and g

This is the conversion buried inside more questions than any other, because orders and stock labels often use different units on purpose. A drug ordered in grams may be stocked in milligrams; a drug ordered in milligrams may be stocked as micrograms per tablet.

• g to mg: multiply by 1000. 0.5 g = 500 mg; 2 g = 2000 mg.
• mg to mcg: multiply by 1000. 0.25 mg = 250 mcg; 0.125 mg = 125 mcg.
• mcg to mg: divide by 1000. 500 mcg = 0.5 mg; 50 mcg = 0.05 mg.
• mg to g: divide by 1000. 1500 mg = 1.5 g; 250 mg = 0.25 g.

Pounds to kilograms: the one you will use most

Weight-based dosing (mg per kilogram) and pediatric dosage calculations both start by converting the client's weight from pounds to kilograms. The rule is divide pounds by 2.2. To go the other way, multiply kilograms by 2.2.

• 154 lb / 2.2 = 70 kg
• 66 lb / 2.2 = 30 kg
• 50 kg x 2.2 = 110 lb
• A quick sanity check: a person's weight in kilograms is always the smaller number, roughly half the pounds. If your kilogram figure is larger than the pounds, you divided the wrong way.

Household and volume conversions

Discharge teaching often lives in household units, because that is what a family has in the kitchen. A caregiver measures in teaspoons and tablespoons, so you convert the ordered milliliters into the spoon they will actually use. The anchor is 1 teaspoon equals 5 mL.

• 1 tsp = 5 mL, so 2 tsp = 10 mL and 3 tsp = 15 mL
• 1 tbsp = 15 mL (the same as 3 tsp)
• 1 fluid oz = 30 mL (2 tbsp)
• 1 cup = 240 mL (8 oz)
• Reach for a household teaspoon, not a kitchen spoon, when teaching: an ordinary spoon is not an accurate 5 mL measure, so teach families to use an oral syringe or a marked dosing cup.

A note on grains

Grains (gr) are an older apothecary unit that still shows up on a few drug labels, most famously aspirin and some thyroid preparations. The nursing-school convention is 1 grain equals about 60 mg, though some references round it to 65 mg (that is why a 5-grain aspirin tablet is labeled 325 mg). Because the value is not exact, the exam gives you a stated equivalent when it matters, and the practice drill below never auto-scores a grain conversion.

Temperature: Celsius and Fahrenheit

Vital-sign questions sometimes give a temperature in the unit you do not want. Two formulas cover it: ==F = (C x 9/5) + 32 and C = (F - 32) x 5/9==. The two anchors worth memorizing are a normal 37 degrees C = 98.6 degrees F, and the fever threshold 38 degrees C = 100.4 degrees F.

• 37 C = 98.6 F (normal core temperature)
• 38 C = 100.4 F (the common fever cutoff)
• 40 C = 104 F (high fever, report it)
• To go C to F, multiply by 9/5 and add 32. To go F to C, subtract 32 first, then multiply by 5/9.

Practice: the free conversion drill

Conversions stick through repetition, not rereading. Tap a family or leave it on Mixed, work the conversion in your head, then reveal the answer with the step. Every problem is generated fresh and the answer is computed from the numbers shown, so you can run it as long as you like.

How the NCLEX hides a conversion inside a dosage question

The exam rarely asks you to convert for its own sake. It buries the conversion inside a dosage calculation or a pharmacology item, where the order and the stock are in different units and the first move is to make them match. Convert to one unit, then apply the formula.

• Every metric step is 1000. kg to g, g to mg, and mg to mcg each multiply by 1000; reverse the direction and you divide by 1000.
• Pounds to kilograms is divide by 2.2. It is the first step of nearly every weight-based dose, and the kilogram figure is always the smaller number.
• Know the household anchors. 1 tsp = 5 mL, 1 tbsp = 15 mL, 1 oz = 30 mL, 1 cup = 240 mL, and 1 mL = 1 cc.
• Convert before you calculate. Most dosage questions bury a unit change; match the order and the stock to one unit first, then apply the formula.