Infusion Rate Calculator
Calculate the pump rate in mL/hour for a weight-based infusion (e.g. dopamine, heparin, insulin, norepinephrine).
Calculate the infusion rate in mL/hr for weight-based dosing.
Formula
Rate (mL/hr) = (Dose per kg/min × Weight × 60) ÷ Concentration (mcg/mL or mg/mL)
Match units carefully: convert mcg ↔ mg as needed before substituting. Common in critical-care vasopressor and sedation infusions.
Step-by-step method
- 1
Identify the prescribed rate
Note the prescribed dose, e.g. 5 mcg/kg/min (dopamine) or 18 units/kg/hr (heparin).
- 2
Identify the bag concentration
Concentration = drug amount ÷ bag volume (e.g. 200 mg in 250 mL = 0.8 mg/mL = 800 mcg/mL).
- 3
Convert to consistent units
Match dose units to concentration units before dividing (mcg with mcg, mg with mg).
- 4
Apply the formula
Rate (mL/hr) = (Dose/kg/min × Weight × 60) ÷ Concentration.
- 5
Cross-check the rate
Sanity-check the rate against typical adult ranges (e.g. dopamine 2–20 mcg/kg/min) and your local infusion protocol before programming the pump.
Worked example
Scenario: Dopamine 5 mcg/kg/min for an 80 kg patient. Bag: 400 mg in 250 mL.
Answer: Concentration = 1600 mcg/mL. Rate = (5 × 80 × 60) ÷ 1600 = 15 mL/hr.
Practice calculations for the NAPLEX
350+ exam-style calculation questions with detailed explanations, mapped to NABP NAPLEX competency Area 4 (Perform Calculations).