IV Drip Rate Calculator (gtt/min)
10 gtt/mL (Macrodrip)
15 gtt/mL (Macrodrip)
20 gtt/mL (Macrodrip)
60 gtt/mL (Microdrip)
Please enter valid positive numbers for volume and time.
IV Drip Rate
0 gtt/min
(Drops per minute)
Infusion Rate
0 mL/hr
(Milliliters per hour)
How to Calculate IV Drip Rate Formula
In clinical settings, accurately calculating the intravenous (IV) drip rate is a fundamental nursing skill required to ensure patient safety. While modern electronic infusion pumps handle many of these calculations automatically, knowing how to manually calculate the drip rate (drops per minute or gtt/min) is essential for gravity infusions and verifying pump settings.
This calculator helps nursing students and medical professionals determine the correct flow rate based on the volume to be infused, the time allotted, and the drop factor of the tubing being used.
The IV Drip Rate Formula
To calculate drops per minute, you need three pieces of information: the total volume of fluid (in milliliters), the drop factor of your IV tubing (drops per milliliter), and the total time of infusion (in minutes).
Drip Rate (gtt/min) =
(Total Volume (mL) × Drop Factor (gtt/mL)) / Time (minutes)
(Total Volume (mL) × Drop Factor (gtt/mL)) / Time (minutes)
Understanding the Variables
- Total Volume (mL): The amount of fluid ordered by the physician (e.g., 1000 mL of Normal Saline).
- Drop Factor (gtt/mL): This number is printed on the packaging of the IV tubing set. It indicates how many drops it takes to equal 1 milliliter.
- Macrodrip sets: Usually 10, 15, or 20 gtt/mL. Used for general IV administration and faster rates.
- Microdrip sets: Always 60 gtt/mL. Used for pediatric patients or precise medications where slow rates are required.
- Time (minutes): The duration over which the fluid must be infused. If the order is in hours, you must convert it to minutes by multiplying by 60.
Example Calculation
Let's look at a practical example. A doctor orders 1000 mL of D5W to be infused over 8 hours. The available IV tubing set has a drop factor of 15 gtt/mL.
- Convert hours to minutes: 8 hours × 60 minutes = 480 minutes.
- Apply the formula: (1000 mL × 15 gtt/mL) / 480 minutes.
- Calculate numerator: 15,000.
- Divide by time: 15,000 / 480 = 31.25.
- Round to nearest whole number: Since you cannot count a fraction of a drop, round to 31 gtt/min.
Setting the Flow Rate Manually
Once you have calculated the rate (e.g., 31 gtt/min), you adjust the roller clamp on the IV tubing while watching the drip chamber. You count the drops falling for 15 seconds and multiply by 4 (or count for 60 seconds) to ensure the rate matches your calculation.
Note: Always adhere to your facility's protocols and double-check calculations for high-alert medications.