Dosage Calculation Mastery for NCLEX
The handful of dosage calc formulas the NCLEX uses. Worked examples for each.
Dosage calc on the NCLEX is straightforward once you know the patterns. Five formulas cover most questions.
Basic ratio (D/H × V)
Desired / Have × Volume. Order: morphine 5 mg. Have: 10 mg/mL. Give: 5/10 × 1 = 0.5 mL.
Weight-based (mg/kg)
Convert lb to kg (÷ 2.2). Multiply mg/kg × kg = total dose. Compare to safe range.
IV drip rate (mL/h)
Volume / hours = mL/h. 1000 mL over 8 h = 125 mL/h.
IV drop rate (gtt/min)
(Volume × drop factor) / minutes. 1000 mL × 15 gtt/mL / 480 min = 31 gtt/min.
mcg/kg/min (drip)
(Dose mcg/kg/min × kg × 60) / concentration mcg/mL = mL/h. Used for vasoactive drips (dopamine, norepi).
Frequently asked
Round to whole or decimal?
Liquid meds usually to nearest tenth. IV drops to whole number. Follow facility policy.
Calculator allowed on NCLEX?
Yes, on-screen calculator built into testing platform.
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