Pharmacy Unit Converter

Formula

mcg × 1000 = ng mg × 1000 = mcg g × 1000 = mg kg × 1000 = g lb × 0.4536 = kg

Always check the units on the prescription, vial, and pump together to avoid 1000-fold errors. Pound ↔ kilogram conversion is high-yield in US pediatric dosing.

Step-by-step method

1. 1

   Identify the source and target unit

   Read the unit on the prescription and the unit you need to convert to (e.g. mg → mcg, lb → kg).

2. 2

   Use a metric ladder for SI mass / volume

   Each step (kg ↔ g ↔ mg ↔ mcg ↔ ng) is a factor of 1000. Move down the ladder → multiply by 1000; move up → divide by 1000.

3. 3

   Use 0.4536 for lb → kg

   Multiply pounds by 0.4536 to get kilograms (1 kg = 2.2046 lb). Critical in pediatric weight-based dosing.

4. 4

   Watch the decimal point

   Misplacing a decimal is the most common cause of 10-, 100-, or 1000-fold dosing errors. Write the conversion explicitly.

5. 5

   Double-check with a colleague

   For high-risk drugs (insulin, opioids, chemotherapy) ask another pharmacist or nurse to independently verify the conversion.

Worked example

Scenario: Convert 0.5 mg to mcg, and 154 lb to kg.

Answer: 0.5 × 1000 = 500 mcg. 154 × 0.4536 = 69.85 kg.