IV Drip Rate Calculator (gtt/min)
Hours
Minutes
10 gtt/mL (Macro)
15 gtt/mL (Macro)
20 gtt/mL (Macro)
60 gtt/mL (Micro)
Calculated Drip Rate:
drops per minute (gtt/min)
Understanding the IV Drip Rate Calculation Formula
In clinical practice, calculating the correct intravenous (IV) flow rate is critical for patient safety. When an infusion pump is not available, nurses must manually calculate the drip rate to set the gravity infusion. This tool uses the standard medical formula to determine how many drops per minute (gtt/min) should fall into the drip chamber.
The IV Flow Rate Formula
To calculate the drip rate manually, you need to know the total volume to be infused, the time over which it should be infused, and the drop factor of the tubing being used. The standard formula is:
Drip Rate (gtt/min) = [Total Volume (mL) × Drop Factor (gtt/mL)] / Time (minutes)
Key Components Explained
- Total Volume: The total amount of fluid or medication in milliliters (mL) ordered by the physician.
- Time: The duration of the infusion converted into minutes. (e.g., 1 hour = 60 minutes).
- Drop Factor: The number of drops it takes to equal 1 mL. This is printed on the IV tubing package. Common macro-drip factors are 10, 15, or 20 gtt/mL, while micro-drip tubing is always 60 gtt/mL.
Example Calculation
Scenario: A doctor orders 1,000 mL of Normal Saline to be infused over 8 hours. The IV administration set has a drop factor of 15 gtt/mL.
- Step 1: Convert time to minutes. 8 hours × 60 minutes = 480 minutes.
- Step 2: Multiply Volume by Drop Factor. 1,000 mL × 15 gtt/mL = 15,000 drops.
- Step 3: Divide by Time. 15,000 / 480 minutes = 31.25 gtt/min.
- Rounding: Since you cannot count a partial drop, round to the nearest whole number: 31 gtt/min.
Standard Drop Factors Reference
| Tubing Type | Drop Factor | Common Use |
|---|---|---|
| Macro-drip | 10, 15, 20 gtt/mL | Routine adult infusions |
| Micro-drip | 60 gtt/mL | Pediatrics or precise meds |