Dosage Calculation Review

Master the fundamental formulas required for safe nursing practice. Each guide includes standardized clinical notations and micro-rationales.

Basic Dosage

Reference Guide

(Desired / Have) * Volume = Dose
- Universal calculation for oral/liquid meds
- Always verify units match before solving
- Round liquid mL to nearest tenth

IV Flow Rate (Gravity)

Reference Guide

(Vol * Drop Factor) / Time = gtt/min
- Time must be converted to minutes
- Drop factor is found on tubing package
- Round to nearest whole number

Weight-Based

Reference Guide

kg * (mg / kg) = Total Dose
- Convert lbs to kg first (1 kg = 2.2 lbs)
- Recalculate with every weight change
- Watch for safe dose range limits

Critical Safety Checkpoints

Unit Conversions

  • - 1 gram (g) = 1,000 milligrams (mg)
  • - 1 milligram (mg) = 1,000 micrograms (mcg)
  • - 1 liter (L) = 1,000 milliliters (mL)
  • - 5 milliliters (mL) = 1 teaspoon (tsp)

Rounding Rules

Standard nursing practice dictates rounding down for safe dosing in high-risk meds, but standard exams (NCLEX) follow mathematical rounding.

  • - Drops (gtt) always whole numbers
  • - mL (greater than 1) to tenth
  • - mL (less than 1) to hundredth