Infusion Rate Calculator
Calculate the pump rate in mL/hour for a weight-based infusion (e.g. dopamine, heparin, insulin).
Calculate the infusion rate in mL/hr for weight-based dosing.
Formula
Rate (mL/hr) = (Dose per kg/min × Weight × 60) ÷ Concentration (mg/mL or mcg/mL)
Match units carefully: convert mcg ↔ mg as needed before substituting.
Step-by-step method
- 1
Identify the prescribed rate
Note the prescribed dose, e.g. 5 mcg/kg/min or 18 units/kg/hr.
- 2
Identify the bag concentration
Concentration = drug amount ÷ bag volume (e.g. 200 mg in 50 mL = 4 mg/mL = 4000 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 and your local infusion protocol before programming the pump.
Worked example
Scenario: Dopamine 5 mcg/kg/min for an 80 kg patient. Bag: 200 mg in 50 mL.
Answer: Concentration = 4000 mcg/mL. Rate = (5 × 80 × 60) ÷ 4000 = 6 mL/hr.
Practice calculations for the CRA
500+ exam-style calculation questions with detailed explanations, mapped to the GPhC Common Registration Assessment Part 1.