IV Flow Rate Calculator (mL/hr)
Calculate the infusion rate for intravenous fluids and medications.
Calculated Flow Rate:
How to Calculate Flow Rate in mL/hr
Calculating the flow rate in milliliters per hour (mL/hr) is a fundamental skill in nursing and clinical practice. It ensures that patients receive the correct volume of intravenous (IV) fluids or medication over a specific period. This is often programmed into an infusion pump.
The mL/hr Flow Rate Formula
The standard mathematical formula for calculating the hourly infusion rate is simple:
If the time is provided in minutes, you must first convert it to hours by dividing the minutes by 60, or use the following variations:
- Flow Rate (mL/hr) = (Total Volume in mL ÷ Total Minutes) × 60
Step-by-Step Practical Example
Let's look at a realistic clinical scenario:
Step 1: Identify the Volume = 500 mL.
Step 2: Identify the Time = 4 hours.
Step 3: Apply the formula: 500 mL ÷ 4 hours = 125 mL/hr.
Example Using Minutes
If you need to infuse 100 mL of an antibiotic over 30 minutes, the calculation would be:
Why Precise Calculation Matters
In medical settings, accuracy is paramount. Using an infusion pump requires an input in mL/hr. Incorrect calculations can lead to fluid overload (hypervolemia) or under-dosage, which can delay treatment effectiveness or cause serious complications. Always double-check your math and verify against the physician's order.
Manual Drip Rates vs. mL/hr
While mL/hr is used for electronic pumps, manual IV setups require calculating "drops per minute" (gtt/min). To find gtt/min, you would take your calculated mL/hr, multiply by the drop factor of the tubing (e.g., 10, 15, or 60 gtt/mL), and divide by 60 minutes.