How to Calculate Rate of Infusion Pump
Calculating the correct infusion rate is a critical skill for nurses and healthcare professionals to ensure patient safety. Whether you are setting an electronic infusion pump or calculating drip rates for gravity-fed IV lines, understanding the underlying formulas is essential.
This calculator determines both the Flow Rate (measured in milliliters per hour for pumps) and the Drip Rate (measured in drops per minute for manual tubing).
Infusion Pump Formula (mL/hr)
Electronic infusion pumps are programmed to deliver a specific volume of fluid over a set period of time. The standard unit of measurement is milliliters per hour (mL/hr).
The Formula:
Example Calculation:
If a doctor orders 1,000 mL of Normal Saline to be infused over 8 hours:
- Volume = 1,000 mL
- Time = 8 hours
- Calculation: 1,000 ÷ 8 = 125 mL/hr
IV Drip Rate Formula (gtt/min)
When an electronic pump is unavailable, nurses must manually regulate the flow using the roller clamp on the IV tubing. To do this, you must calculate drops per minute (gtt/min). This requires knowing the Drop Factor of the tubing, which is found on the packaging (e.g., 10, 15, 20, or 60 gtt/mL).
The Formula:
Example Calculation:
Using the same order (1,000 mL over 8 hours) with tubing that has a drop factor of 15 gtt/mL:
- Convert time to minutes: 8 hours × 60 = 480 minutes.
- Multiply Volume by Drop Factor: 1,000 × 15 = 15,000.
- Divide by Time in Minutes: 15,000 ÷ 480 = 31.25.
- Round to the nearest whole number: 31 gtt/min.
Common Drop Factors
- Macrodrip (10, 15, 20 gtt/mL): Used for delivering large volumes or fast rates. Commonly used for standard adult IV hydration.
- Microdrip (60 gtt/mL): Used for small volumes, precise medication administration, or pediatric patients. Note: With 60 gtt tubing, the gtt/min is equal to mL/hr.
Why Accuracy Matters
Incorrect infusion rates can lead to serious complications. Infusing too fast (fluid overload) can cause heart failure or pulmonary edema, while infusing too slow can result in dehydration or inadequate medication therapy. Always double-check your calculations and verify the pump settings against the physician's order.