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 gtt/mL (typically 10, 15, or 20 for macro-drip; 60 for micro-drip).
Step-by-step method
- 1
Note the volume to be infused
Read the prescribed volume in milliliters (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
Common US adult macro-drip sets are 10, 15, or 20 gtt/mL. Pediatric / micro-drip sets are 60 gtt/mL. Check the tubing packaging.
- 4
Apply the formula
Drip rate (gtt/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 15 gtt/mL giving set.
Answer: (1000 × 15) ÷ (8 × 60) = 31.25 ≈ 31 gtt/min.
Practice calculations for the NAPLEX
350+ exam-style calculation questions with detailed explanations, mapped to NABP NAPLEX competency Area 4 (Perform Calculations).