IV drip rate (gtt/min)
With a gravity IV, you count the drops. Find the drops each minute from the volume, the time and the drop factor of the set.
For practice only. Not for clinical use. The drug names and numbers are made up. Always follow your school's and your facility's rules.
Practice problem
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The order is 1,000 mL IV over 9 hours. The tubing gives 15 drops per mL (gtt/mL). How many drops per minute do you set?
Round to the nearest whole number.
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How to solve it
Drip rate in gtt/min equals the volume in mL times the drop factor in gtt/mL, divided by the time in minutes. If the time is in hours, multiply it by 60 first.
Worked example
The order is 2,000 mL IV over 11 hours. The tubing gives 10 drops per mL (gtt/mL). How many drops per minute do you set?
Solution
- 11 h × 60 = 660 min.
- (2,000 mL × 10 gtt/mL) ÷ 660 min = 30.303 gtt/min, rounded to 30 gtt/min.
Formula: gtt/min = (volume in mL × drop factor) ÷ time in minutes
Answer: 30 gtt/min
Questions
What is a drop factor?
The drop factor is the number of drops in 1 mL. It is printed on the package of the IV set. It is in gtt/mL.
What is the difference between macro and micro sets?
A macro set gives big drops. Common sizes are 10, 15 and 20 gtt/mL. A micro set gives small drops. It has 60 gtt/mL.
How do I find the drops each minute?
Multiply the volume in mL by the drop factor. Divide by the time in minutes.
How do I round drops?
You cannot count part of a drop. Round to the nearest whole drop, unless the problem says something else.