How it's calculated
mL = mg ÷ d (reverse: mg = mL × d)
mg = mass in milligrams, mL = volume, d = density or concentration in mg/mL (water = 1000, e.g. a 100 mg/5 mL syrup = 20).
Common questions
Why can't you convert mg to mL without density?
Milligrams measure mass and milliliters measure volume. You need a density or a concentration to bridge the two.
How does it work for liquid medicines?
It uses the drug concentration, like 100 mg per 5 mL, to turn a target dose in mg into a volume in mL.