Infusion Rate Per Hour Calculator
Calculate IV flow rates in mL/hr and drops per minute (gtt/min).
Calculation Results:
How to Use the Infusion Rate Per Hour Calculator
Calculating the correct infusion rate is a critical skill in healthcare, ensuring patients receive fluids and medications at the prescribed pace. This calculator simplifies the process by providing both the hourly rate (mL/hr) and the drip rate (gtt/min).
The Infusion Rate Formula
To determine the hourly rate manually, you can use the following standard formulas:
- Infusion Rate (mL/hr): Total Volume (mL) ÷ Total Time (hr)
- Flow Rate (gtt/min): [Total Volume (mL) × Drop Factor (gtt/mL)] ÷ [Total Time (minutes)]
Common Drop Factors
The "Drop Factor" refers to the number of drops it takes to equal 1 mL of fluid, which is determined by the IV tubing used:
| Tubing Type | Drop Factor (gtt/mL) |
|---|---|
| Macrodrip (Standard) | 10, 15, or 20 gtt/mL |
| Microdrip (Pediatric) | 60 gtt/mL |
Practical Examples
Example 1: A doctor orders 1,000 mL of Normal Saline to be infused over 8 hours using a 20 gtt/mL set.
- mL/hr: 1,000 mL ÷ 8 hours = 125 mL/hr
- gtt/min: (1,000 mL × 20) ÷ (8 × 60 minutes) = 20,000 ÷ 480 = 41.67 gtt/min
Example 2: 500 mL of D5W over 4 hours with a microdrip (60 gtt/mL) set.
- mL/hr: 500 mL ÷ 4 hours = 125 mL/hr
- gtt/min: (500 mL × 60) ÷ (4 × 60 minutes) = 30,000 ÷ 240 = 125 gtt/min
Why Precision Matters
In clinical environments, an incorrect infusion rate can lead to fluid overload or sub-therapeutic dosing. While automated IV pumps handle much of this work today, manual calculation remains an essential backup skill for emergency situations or settings where electronic pumps are unavailable. Always double-check calculations with a second healthcare professional whenever possible.