IV Flow Rate Calculator
Calculate IV infusion rates in mL per hour and drops per minute for gravity sets.
About the IV Flow Rate Calculator
Enter the volume to infuse, the time it should run over and the drop factor of the giving set. The calculator gives the pump rate in mL/h and the drip rate in drops per minute, both exact and rounded.
Infusion pumps are set in mL/h. Gravity drips are counted in drops per minute, using the drop factor printed on the giving set: macro sets are usually 10, 15 or 20 drops per mL, and micro sets 60.
The formula
Drops/min = volume (mL) × drop factor ÷ time (min)
- drop factor
- drops per mL, printed on the giving-set packaging (gtt/mL)
- time
- in minutes (hours × 60)
Worked example
1,000 mL over 8 hours with a 15 gtt/mL set
- Pump rate: 1,000 ÷ 8 = 125 mL/h
- Drip rate: 1,000 × 15 ÷ 480 = 31.25 drops/min
- Set to 31 drops a minute
Things to keep in mind
- For training and double-checking only; follow your institution's protocols.
Questions people ask
Why round drops per minute?
You can only count whole drops, so round to the nearest whole number.
With a 60 gtt/mL set, is mL/h equal to drops/min?
Yes, with micro-drip sets the two numbers are the same.
How do I count drops?
Count drops in the chamber for 15 seconds and multiply by 4, then adjust the roller clamp.