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You know that feeling when the doctor prescribes a liquid medication for your kid and you’re scratching your head over how much to actually measure out? Been there, done that way too many times.

The prescription label shows the concentration, like 250mg per 5mL for amoxicillin suspension. But then it says your child’s dose is 375mg. How do you get from the mg amount to knowing how many mLs to draw up and give them?

Here’s the trick I’ve learned over the years of being a mom and giving kids’ meds. Take that mg dose number and divide it by the first part of the concentration – the mg amount.

In our example: 375mg divided by 250mg and multiply by 5ml = 7.5ml check

So for a 375mg dose, you’d measure out 7.5mL of the liquid.

It’s algebraic math magic! But it makes total sense when you think it through. The concentration tells you how many mgs are packed into each mL.

So you’re really just calculating:

( dose I need in mg / mg ) × mL = mL i have to measure

Pharmacists can probably explain it more technically. But this mental trick has been a total lifesaver for me over the years with multiple kids and all their liquid meds. No more head scratching!

I’d still double check my math, especially for the littlest ones. But using this method has prevented so many potential dosing mix-ups in our house. Hopefully it can help other parents too when the dosage directions have you crosseyed!

How to convert milligrams to milliliters if the density is known (mg to mL)

To convert milligrams to milliliters, divide the weight of the product by its density times 1000. Let ‘s write this in the form of a formula:

{mL = \dfrac{mg}{density \cdot 1000}}

For example, let’s convert 100mg of cold water into milligrams. The density of water at a temperature of 39.2°F / 4.0°C is 1 g/mL.

{100 mg = \dfrac{100}{1 \cdot 1000} = \dfrac{100}{1000} = \dfrac{1}{10} = 0.1 mL}

This conversion is much easier to do on a calculator – try it .

What is milligram?

Milligram is a unit of mass equal to ¹/₁₀₀₀ gram. Milligram is abbreviated as mg.

What is milliliter?

Milliliter is a unit of capacity equal to ¹/₁₀₀₀ liter. Milliliter is abbreviated as ml or mL.

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