IV Drip Rate: Formula & How to

Nursing Knowledge

IV Drip Rate: Formula & How to

Accurate drip rate calculation impacts therapeutic outcomes and is a fundamental aspect of clinical nursing responsibilities. It involves determining the number of drops per minute (gtts/min) based on health care provider orders, the total volume of fluid to be infused, the infusion duration, and the drop factor specific to the IV tubing used. Mastering this calculation is essential for patient safety, especially when electronic infusion devices are not in use. Download this IV drip rate cheat sheet to never forget how to do it again!
Last updated: December 4, 2023

Table of contents

What is IV drip rate? 

IV drip rate describes the rate at which an intravenous infusion is administered in drops per minute.

Use of an IV pump to automatically control the rate of infusion is now common in most medical settings in the United States; however, an IV pump may not be available in some settings/emergencies. In these situations, it is important that nurses know how to calculate the IV drip rate and set the rate of infusion using the IV tubing roller clamp.

How to select the correct tubing type

Factors such as client age and size will guide selection of IV tubing. Different tubing types deliver a larger or smaller number of drops per milliliter. Pediatric clients are very sensitive to fluid volume, so microdrip tubing is used to tightly control fluid volume administration (60 gtt(mL). Macrodrip tubing (10, 15, or 20 gtt/mL) is typically used for adult clients.

What is the drop factor? 

The drop factor (or drip factor) refers to the number of drops (gtts) that make up one milliliter of fluid. Specific to the type of IV tubing being used (typically indicated on the packaging), it is used to calculate the flow rate for manual IV infusions. 

Example order for IV infusion

Typically, the order will include the volume of medication or fluid to be infused and either a rate per hour or the overall duration of the infusion.

It is your job as the nurse to use this information to determine the IV drip rate in gtt/min.

Sample order:

0.9% normal saline, 1000 mL IV over 8 hr

How to calculate IV flow rate: Drops per minute 

We are using the example order of 0.9% normal saline, 1000 mL IV over 8 hr for the calculation. The drop factor is 10 gtts/mL.

Step 1: Convert time units to get the total infusion time in minutes 

Total infusion time in minutes: The order states 8 hours, which is calculated by multiplying 60 minutes x 8 hours, equaling 480 minutes overall. 

Step 2: Calculate gtt per minute with the IV drip rate formula


$$ Drip\ rate\ (gtt/min) = \frac{(Total\ volume\ [mL]) \times (Drop\ factor\ [gtt/mL])}{Time\ [minutes]} $$
  • The total volume is given in the order. 
  • The drop factor is determined by the use of the correct tubing, which is required for the calculation.
  • The time is the overall infusion time in minutes. 
$$ Drip\ rate\ (gtt/min) = \frac{1000\ mL \times 10\ gtt/mL}{480\ min} $$ $$ Drip\ rate (gtt/min) = \frac{10000\ gtt}{480\ min} $$ $$ Drip\ rate\ (gtt/min) =\ 20.8\ gtt/min\ =\ 21\ gtt/min $$

Since you can’t actually administer a fraction of a drop, if you get a fraction as a result, round to the nearest whole number. 

How to set the drip rate

To set the IV drip rate, count the drops as fluid enters the drip chamber. Adjust the roller clamp until you count the correct number of drops entering the chamber per minute (21 for our example above). For safety, label IV bag with the ordered rate and time the hourly markings for infusion.


IV Drip Rate: Formula & How to

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Nursing Cheat Sheet

Variables of IV drip rate calculation including tubing type, drop factor, and fluid order, along with sample calculation and instructions for setting drip rate using roller clamp.

Master the topic with a unique study combination of a concise summary paired with video lectures. 

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