IV Drip Rate Calculator
Calculate intravenous drip rate in drops per minute given volume, infusion time, and the drop factor of the giving set.
Calculate the IV drip rate in drops per minute based on volume, infusion time, and drop factor.
Formula
Drip rate (drops/min) = (Volume × Drop factor) ÷ (Time × 60)
Volume in mL, time in hours, drop factor in drops/mL (20 for standard, 60 for micro-drip).
Step-by-step method
- 1
Note the volume to be infused
Read the prescribed volume in millilitres (e.g. 1000 mL of 0.9% sodium chloride).
- 2
Note the infusion time
Read the prescribed time in hours (e.g. infuse over 8 hours). Convert minutes to hours if needed.
- 3
Identify the drop factor of the giving set
Standard adult macro-drip sets are 20 drops/mL. Paediatric / micro-drip sets are 60 drops/mL. Check the packaging.
- 4
Apply the formula
Drip rate (drops/min) = (Volume × Drop factor) ÷ (Time in hours × 60).
- 5
Round and verify
Round to the nearest whole drop. Sanity-check that the rate matches the intended infusion duration.
Worked example
Scenario: Infuse 1000 mL of 0.9% sodium chloride over 8 hours using a 20 drops/mL giving set.
Answer: (1000 × 20) ÷ (8 × 60) = 41.67 ≈ 42 drops/min.
Practice calculations for the CRA
500+ exam-style calculation questions with detailed explanations, mapped to the GPhC Common Registration Assessment Part 1.