Drops Per Minute Calculator
By Michelle Saari MSc, RD, Registered Dietitian
Last Updated on April 11th, 2024
Estimates the intravenous rate at which different fluids should be administered in accordance to a prescription.
Refer to the text below the tool for more information about determining the IV drops per minute.
Purpose
Depending on the volume to be administered, the duration and the established drop factor of an intravenous fluid prescription, the drops per minute rate must be calculated.
Formula
IV Drip rate (Drops per minute) = (Volume to be given in mL x Drop factor in gtts/mL) / Time in minutes
Calculating the drops per minute needed for an intravenous (IV) administration, then our drops per minute calculator can help make this calculation simple for you.
Ensuring that a patient receives the right amount of volume is important for managing their IV fluids and medications.
What is Drops per Minute?
When administering an IV you may know the overall volume that a patient will be receiving, but you need to also calculate how many drops per minute. Most machines that administer IVs will require this number.
There are a few things that you need to know before this calculation. Here are the top 3 items to know:
- The total volume that will be in the IV fluid mixture. This is usually expressed as millimetres (mL).
- Length of time the IV will be administered. This will vary, it may be anywhere from minutes to hours of administration time.
- The drop factor is also important, it needs to be determined what the macrodrip tubing will be. This is usually expressed in gtts/mL.
Drops per Minute formula
If we look at what the formula would be when putting all of these factors together we get:
Drops per Minute Rate = (Total volume in mL x Drop Factor in gtts/min) / Total time administered (in minutes)
This will give you the drops per minute rate, or the rate at which the IV will be administered in minutes.
Let’s illustrate this with an example
If the total volume is 500 mL, the administration time is 60 minutes, and the drop factor is 15 gtts/mL, the drops per minute would be:
Drops per Minute = (500 mL × 15 gtts/mL) / 60 minutes = 125 drops per minute
Common Drops per Minutes and Tubing Types
Most intravenous (IVs) therapies will have one of the most common rates that are observed in clinical settings:
- 10 gtts/mL
- 15 gtts/mL
- 20 gtts/mL
- 60 gtts/mL
60 gtts/mL is more often used when a microdrip tubing is used for an IV, because it is a much thinner tube and has a higher drip factor. Microdrips are used for more precision administration, and macrodrips are used more often for blood transfusions.
The rate however will be patient dependent on their overall health and medical conditions. All drops per minute rates should be confirmed by either a Doctor or Nurse that is working with the patient.
What is the PEACE Method?
Administering an IV is a serious job as many will administer medications, cancer therapies, essential fluids, blood transfusions, and other rehydration therapies.
Many healthcare professionals will use what we call the PEACE method to ensure that they don’t forget any steps when starting an IV. Here is what the acronym stands for.
| PEACE Letters | Represents | Meaning |
| P | Plan | Plan exactly what medication or fluids will be needed, and what the exact dosage is. |
| E | Estimate | Some will estimate the needs before doing their final calculations. |
| A | Approach | Ask yourself what, how, when, and where for all phases of administering an IV. |
| C | Calculate | Complete the exact calculations needed for administering the IV. |
| E | Evaluate | Have another healthcare professional double check all of your calculations for the IV administration before hooking it up. |
Anyone administering an IV should always use a drops per minute calculator and should have another colleague check their work for the safety of their patients.
FAQs on IV Drip Rate Calculations and Drops Per Minute Calculator
To calculate the drops per minute, use the formula:
Drops per Minute = (Total Volume × Drop Factor) / Total Time
For example, if the total volume is 500 mL, the infusion time is 60 minutes, and the drop factor is 15 gtts/mL, the calculation would be:
Drops per Minute = (500 mL × 15 gtts/mL) / 60 minutes = 125 drops per minute
To convert the drip rate from mL/hour to drops per minute, you can use the following formula:
Drops per Minute = (Drip Rate in mL/hour × Drop Factor) / 60
For example, if the drip rate is 100 mL/hour and the drop factor is 20 gtts/mL, the calculation would be:
Drops per Minute = (100 mL/hour × 20 gtts/mL) / 60 = 33.33 drops per minute
Macrodrip tubing typically has a lower drop factor, ranging from 10 to 20 gtts/mL. This type of tubing is commonly used for less critical infusions, such as blood transfusions.
Microdrip tubing has a higher drop factor, usually around 60 gtts/mL. This type of tubing is used for more precise and controlled IV administrations, often in pediatric cases or for medications with a narrow therapeutic range.
The higher the drop factor, the slower the infusion rate will be for a given volume and time.
To ensure accurate drip rate control, follow these steps:
Count the number of drops in the drip chamber for one minute.
Use the roller clamp to adjust the drip rate as needed.
Count the drops again to verify the desired drip rate.
Some IV administration devices may have electronic flow control mechanisms that calculate the drip rate for you. However, it’s still a good practice to double-check the results.
Precise control of the drip rate is crucial to patient safety. Even seemingly harmless solutions, such as saline, can have potentially serious side effects if administered at the wrong rate. Infusion rates that are too fast can lead to complications like encephalopathy, seizures, and paralysis.
It’s especially important to carefully monitor and adjust the drip rate when treating conditions like hyponatremia, where the correction rate should not exceed 6-12 mEq/L in the first 24 hours and 18 mEq/L or less over 48 hours.
References
https://www.nursingcenter.com/ncblog/december-2021/how-to-calculate-drops-per-minute
Written By
Michelle Saari MSc, RD
Registered Dietitian