IV Flow Rate Calculator
Calculate mL/hr and Drip Rates (gtt/min) for Nursing Practice
Mastering IV Flow Rate Calculations
In clinical nursing practice, accurately calculating intravenous (IV) flow rates is a critical skill for medication safety. Rates are generally calculated in two ways: mL/hr (for infusion pumps) and gtt/min (for gravity-fed tubing).
The Standard Formulas
1. Electronic Pump Rate (mL/hr):
Total Volume (mL) ÷ Total Time (hr) = mL/hr
2. Manual Drip Rate (gtt/min):
(Total Volume (mL) × Drop Factor) ÷ Time (minutes) = gtt/min
Essential Drop Factors
The "Drop Factor" refers to how many drops equal 1 mL of fluid, which is determined by the size of the orifice in the drip chamber. It is always printed on the IV tubing package.
- Macrodrip: Typically 10, 15, or 20 gtt/mL. Used for routine adult infusions.
- Microdrip: Always 60 gtt/mL. Used for pediatric or high-precision medications.
Practice Questions & Examples
Practice Question 1: A physician orders 1,000 mL of Normal Saline to be infused over 8 hours. What is the mL/hr rate?
Calculation: 1,000 mL ÷ 8 hours = 125 mL/hr
Practice Question 2: You are using tubing with a drop factor of 15 gtt/mL. You need to infuse 500 mL of D5W over 4 hours. Calculate the drops per minute (gtt/min).
Calculation:
1. Convert 4 hours to minutes: 4 × 60 = 240 minutes.
2. (500 mL × 15 gtt/mL) ÷ 240 min = 7,500 ÷ 240 = 31.25 (31 gtt/min)
Practice Question 3 (Microdrip): An order is written for 100 mL of an antibiotic to run over 30 minutes using microdrip tubing (60 gtt/mL).
Calculation: (100 mL × 60 gtt/mL) ÷ 30 min = 6,000 ÷ 30 = 200 gtt/min
Nursing Tips for Success
- Round Appropriately: Drops per minute must be rounded to the nearest whole number because you cannot count a fraction of a drop.
- Time Units: Always double-check if your "Time" is in hours or minutes before plugging it into the drip rate formula.
- Verification: Always have another licensed nurse double-verify high-alert medication drip rates.