# How to Calculate IV Drip Rates

In this day and age, **electronic IV pumps** have eliminated the need to manually calculate IV drip rates when administering fluids or medications. However, there may be a time **when you do not have a functioning electronic pump** and will need to make the conversions. And, because these fluids or medications are delivered directly to the patient’s bloodstream, there is **little to no room for error**.

## Information You’ll Need

When calculating an IV drip rate, the first step is to **review the order**. If the patient is going to receive fluids, the order will likely be to administer a certain amount of fluids over a specific **amount of time** (ex.: 250 mL/hr). When administering medications intravenously, the order will usually be in **milligrams or micrograms per minute or hour**, depending on the medication and dosage. And the medication will either be **pre-mixed or need to be added** to a bag of IV fluids. This will determine the **concentration** of the medication in either milligrams or micrograms per milliliter of fluid (ex.: 250mg/100mL).

## Tubing Selection

Next, you will select your IV **tubing**, which will depend on whether you are administering a higher **volume** of fluid or a lower volume of fluid. When administering a lower volume of fluid or needing to deliver a precise amount of the medication, you will use a **micro-drip IV tubing set**, which administers 60 drops (gtts) per mL. For higher volumes of fluid, you can use a **macro-drip IV tubing set** and will need to check the **packaging**, as they vary from 10-20 gtts/mL.

## Calculations

Using all of this information, you will perform the necessary **conversions** to calculate the number of drops per minute. As an example, you have an order to administer 150 mcg of Medication A over an hour, and your pharmacy has prepared Medication A in normal saline with a concentration of 750 mcg in 100 mL of normal saline and provided a *microdrip tubing* set.

First, let’s determine the **liquid volume to be infused in an hour**. To convert mcg/hr to mL/hr:

This equates to \(\frac{20 \;\text{mL}}{1 \;\text{hr}}\).

Next, we will determine the **drip rate**. The formula is as follows:

So, in our example, you would do this:

\[\frac{20 \;\text{mL}}{1 \;\text{hr}}\; \times \;\frac{1 \;\text{hr}}{60 \;\text{min}}\; \times\; \frac{60 \;\text{gtt}}{1\; \text{mL}}\]This equates to 20gtt/min *or* 20 drops per minute.

One interesting note: When using a micro-drip tubing set (60 drops per mL), the number of milliliters per hour will equal the number of drops per minute!

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