Simple Metric Conversions For Paramedics and EMTs

You’re in the middle of a call. Sounds like the perfect time for a math quiz on prehospital metric conversions, right? Your local protocols say you need to administer 5μg/kg/min of Dopamine using 60gtt/mL tubing. Now find the surface area of the sun using Einstein’s theory of relativity. (Hint: Aliens don’t wear hats!)

The thought of calculating intricate math problems in our head is enough to give any of us palpitations. The good news is, when you understand the underlying principles, metric conversions for paramedics and other pre-hospital providers is actually just as easy as paying for your morning coffee.

Metric Units

In pre-hospital medicine we focus on three metric units of measurement.

  1. Gram (g) — non-liquid weight
  2. Meter (m) — length
  3. Liter (L or l) — volume

Subunits

And we break down these units of measurement into subunits by adding a prefix.

  • Kilo (k) — one thousand (1,000)
    • Example: 1 kilogram (kg) = 1000 grams
  • Centi (c) — one hundredth (.01)
    • Example: 1 centimeter (cm) = .01 meter
  • Milli (m) — one thousandth (.001)
    • Example: 1 milliliter = .001 liter
  • Micro (mc or μ) — one millionth (.000001)
    • Example: 1 microgram (mcg or μg) = .000001 gram

Conversions

Think about it like this: The metric system is like money and those units of measure are our currency. One U.S. dollar ($1.00) is equal to ten dimes ($0.10) which in turn is equal to ten pennies ($0.01). If you owe $1.00 you can hand over a one dollar bill ($1.00 x 1), ten dimes ($0.10 x 10), or one hundred pennies ($0.01 x 100). Either way, the result is the same; its just a different way of expressing it.

If you’re converting from a smaller unit to a larger unit (i.e. milliliters to liters, micrograms to milligrams, etc.),  divide / move the decimal point to the left.

  • 500 mg =.5 g
  • 2 ml = .002 L
  • 2000 g = 2 kg
  • 250 mcg = .25 mg

1 mcg = .001 mg = .000001 g = .000000001 kg (Or in plain English: One microgram = One thousandth milligram = One millionth gram = One billionth kilogram)

And the opposite is true that if you are converting from a larger unit to a smaller unit (i.e. grams to milligrams), move the decimal point to the right.

  • 50 g = 50000 mg
  • 200 kg = 200000 g
  • 7 mg = 7000 mcg

1 kg = 1,000 g = 1,000,000 mg = 1,000,000,000 mcg (Or: One kilogram = One thousand grams = One million milligrams = One billion micrograms)

See? Making metric conversion calculations is the same underlying principle as counting out your change to pay for your fourth triple shot espresso of the shift. Now we know it wasn’t the math that was giving you palpitations. It was all the caffeine!