Med MathPractice test

Unit conversions for nurses

Most dose math starts with the same units. Practice grams, milligrams, micrograms, liters, milliliters, pounds and kilograms.

For practice only. Not for clinical use. The drug names and numbers are made up. Always follow your school's and your facility's rules.

Practice problem

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A patient weighs 86 lb. What is the weight in kg?

Round to the nearest tenth.

kg

How to solve it

Find the conversion factor. Multiply when you go to a smaller unit. Divide when you go to a bigger unit. Remember: 1 g = 1,000 mg. 1 mg = 1,000 mcg. 1 L = 1,000 mL. 1 kg = 2.2 lb.

Worked example

Convert 2 g to mg.

Solution

  1. 1 g = 1,000 mg. Multiply by 1,000.
  2. 2 g × 1,000 mg/g = 2,000 mg.

Formula: mg = g × 1,000

Answer: 2,000 mg

Questions

How do I change grams to milligrams?

Multiply by 1,000. For example, 2 g is 2,000 mg. To go back, divide by 1,000.

How do I change micrograms to milligrams?

Divide by 1,000. For example, 500 mcg is 0.5 mg. Always write a zero before the point.

How do I change pounds to kilograms?

Divide the pounds by 2.2. For example, 154 lb is 70 kg. To go the other way, multiply the kilograms by 2.2.

How many mL are in a liter?

There are 1,000 mL in 1 L.

More practice

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