IV Flow Rate Calculator - mL/h and Drops per Minute (gtt/min)
IV Flow Rate Calculator
Infusion rate in mL per hour and drops per minute
mL/h and gtt/min
The pump rate and the gravity drip rate from the same inputs.
Common Drop Factors
10, 15 and 20 gtt/mL macro sets and 60 gtt/mL micro sets.
Finish Time
See how long the infusion runs and when it will finish.
Private
Calculated in your browser.
The Formulas
For an infusion pump, rate (mL/h) = volume (mL) ÷ time (h). For a gravity set, drops per minute = volume (mL) × drop factor (gtt/mL) ÷ time (min). Example: 1,000 mL over 8 hours is 125 mL/h; with a 20 gtt/mL set that is 1,000 × 20 ÷ 480 = 41.7, rounded to 42 drops per minute, about one drop every 1.4 seconds.
The drop factor is printed on the giving set packaging. Macro sets deliver larger drops and suit routine adult fluids; micro sets (60 gtt/mL) suit small or precise volumes, and with them drops per minute equal mL per hour. Gravity infusions drift with patient position and line height, so recheck them regularly. This tool helps you practise and double-check calculations; it is never a substitute for the prescription and local policy.
Key Takeaways
- Check the set: The drop factor is on the packaging.
- Micro sets: At 60 gtt/mL, drops per minute equal mL per hour.
- Round sensibly: Drops are counted whole; pumps accept decimals.