IV Drip Rate Calculator
10 gtt/mL (Macrodrip)
15 gtt/mL (Macrodrip)
20 gtt/mL (Macrodrip)
60 gtt/mL (Microdrip)
Custom…
Infusion Rate
—
drops/minute (gtt/min)
Flow Rate
— mL/hr
How to Calculate IV Flow Rate (Drops Per Minute)
In nursing and medical fields, calculating the correct intravenous (IV) flow rate is critical for patient safety. When an infusion pump is not available, nurses must manually calculate the drops per minute (gtt/min) to set the roller clamp on the IV tubing correctly. This calculator helps determine exactly how many drops should fall into the drip chamber every minute to deliver the prescribed volume of fluid over a set period.
The IV Flow Rate Formula
The standard formula used to calculate the drip rate is:
Drops/min = (Total Volume (mL) × Drop Factor (gtt/mL)) / Time (minutes)
Where:
- Total Volume: The amount of fluid prescribed (in milliliters).
- Drop Factor: The calibration of the IV tubing, indicating how many drops make up 1 milliliter (gtt/mL).
- Time: The total duration for the infusion in minutes.
Understanding Drop Factors
The "Drop Factor" is determined by the specific IV tubing set being used. It is printed on the packaging of the tubing.
| Type | Drop Factor (gtt/mL) | Common Uses |
|---|---|---|
| Macrodrip | 10, 15, or 20 gtt/mL | Used for general adult infusions requiring standard fluid rates (>100mL/hr) or thick fluids. |
| Microdrip | 60 gtt/mL | Used for pediatric patients, elderly patients, or when precise, small volumes are needed (<50mL/hr). |
Calculation Example
Let's say a doctor orders 1000 mL of Normal Saline to be infused over 8 hours. The available tubing has a drop factor of 15 gtt/mL.
- Convert time to minutes: 8 hours × 60 minutes = 480 minutes.
- Apply the formula: (1000 mL × 15 gtt/mL) / 480 minutes.
- Calculate: 15,000 / 480 = 31.25.
- Round: Since you cannot count a fraction of a drop, you round to the nearest whole number. The rate is 31 gtt/min.
Why is Manual Calculation Important?
While electronic infusion pumps are common in modern hospitals, they are not infallible and may not always be available (e.g., in field medicine, resource-limited settings, or during power failures). Being able to manually calculate and regulate the IV flow rate ensures that patients receive their medication and fluids at the safe, prescribed speed regardless of technological limitations.