Dosage Practice

Metric Conversions for Nursing: mg, mcg, g, mL and L

Every step in the metric system is a factor of 1,000: 1 g = 1,000 mg, 1 mg = 1,000 mcg, 1 L = 1,000 mL, 1 kg = 1,000 g. Going to a smaller unit, the number gets bigger, so you multiply; going to a larger unit, you divide.

The Formula

1 g = 1,000 mg 1 mg = 1,000 mcg 1 kg = 1,000 g 1 L = 1,000 mL

Each jump is three decimal places.

How to work it out

  1. 1 Decide which direction you are going. Larger unit to smaller unit (g to mg) means the number grows, so multiply by 1,000.
  2. 2 Smaller unit to larger unit (mcg to mg) means the number shrinks, so divide by 1,000.
  3. 3 Move the decimal point three places. Grams to milligrams: 0.25 g becomes 250 mg. Micrograms to milligrams: 1,500 mcg becomes 1.5 mg.
  4. 4 Write a leading zero before a decimal (0.5 mg, never .5 mg) and no trailing zero (2 mg, never 2.0 mg). Write mcg, not µg.

Worked Examples

Example 1

Convert 0.25 g to mg.

  1. Grams to milligrams is larger to smaller, so multiply.
  2. 0.25 g × 1,000 mg/g = 250 mg.

Answer: 250 mg

Example 2

Convert 1,500 mcg to mg.

  1. Micrograms to milligrams is smaller to larger, so divide.
  2. 1,500 mcg ÷ 1,000 mcg/mg = 1.5 mg.

Answer: 1.5 mg

Try five free problems

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Problem 1 of 5No sign-up needed

Convert 1.2 g to mg.

exact answer, no rounding needed

mg

Common Mistakes

  • Moving the decimal two places instead of three

    The metric steps nursing uses are all thousands. 1 g is 1,000 mg, not 100 mg. If your answer is off by a factor of ten, this is usually why.

  • Going the wrong way

    Ask whether the new unit is bigger or smaller. Milligrams are smaller than grams, so there are more of them: the number must get bigger.

  • Writing .5 or 2.0

    Exams, and pharmacies, treat a missing leading zero or a trailing zero as an error, because .5 can be read as 5 and 2.0 as 20. Write 0.5 and 2.

Questions Students Ask

How many mcg are in a mg?

1,000 micrograms make one milligram. Micrograms are written mcg in nursing, never µg, because the µ symbol is easily misread.

Is 1 mL the same as 1 cc?

Yes, one cubic centimeter holds exactly one milliliter. Write mL; cc is on the do-not-use lists because it can be misread.

Why do nursing exams care so much about leading and trailing zeros?

Because a misread decimal point is a tenfold overdose or underdose. The habit is graded because it matters at the bedside.

Keep practicing in lesson 1: Metric Conversions

Fresh numbers every time. Ten correct answers finish the lesson. The first five problems are free, no account needed.

Open lesson 1