Calculate an IV infusion rate in mL/hour and drops per minute from the volume, the time and the drop factor of the giving set.
mL
Enter the values to see the result here.
Calculation aids only. They do not replace clinical judgement or the drug reference. Verify every dose before using it on a patient.
Formula
With volume V in mL, time t in minutes and drop factor F in drops per mL:
drops/min=tV×FmL/h=tV×60
The time between drops is 60/(drops/min) seconds.
Worked example
Give 1000 mL of saline over 8 hours with a 20 drops per mL set.
Time in minutes: 8×60=480.
drops/min=1000×20/480=41.7, rounded to 42.
mL/h=1000/480×60=125.
That is about one drop every 1.4 seconds.
Common mistakes
Using the wrong drop factor. Read it from the giving set packaging, not from memory.
Entering hours where minutes are expected. Use the two time boxes together, for example 1 hour and 30 minutes.
Forgetting to recalculate when the bag is slowed or paused and the remaining time changes.
Relying on gravity drip for high-risk drugs instead of a pump.
Frequently asked questions
What is a drop factor?
It is the number of drops that make up 1 mL for a particular giving set, printed on the packaging. Common values are 10, 15 and 20 drops per mL for standard sets and 60 for paediatric micro-drip sets.
Why are drops per minute whole numbers?
You can only count whole drops, so the rate is rounded. For slow infusions, count for a full minute rather than a few seconds, or use an infusion pump, which is more accurate.
Can I use this for drugs with a dose per kilogram?
Not directly. First work out the dose and the volume of drug solution it needs, then use the volume and the time here. For high-risk infusions such as insulin or heparin always use a pump and a second check.