Please enter a valid volume and time greater than zero.
Infusion Pump Setting
0 mL/hr
function calculateFlowRate() {
// Get input values
var volumeInput = document.getElementById('iv_volume');
var hoursInput = document.getElementById('iv_hours');
var minutesInput = document.getElementById('iv_minutes');
var resultContainer = document.getElementById('iv_result_container');
var resultDisplay = document.getElementById('iv_result_display');
var summaryDisplay = document.getElementById('iv_summary');
var errorMsg = document.getElementById('iv_error_msg');
var volume = parseFloat(volumeInput.value);
var hours = parseFloat(hoursInput.value);
var minutes = parseFloat(minutesInput.value);
// Normalize inputs (treat NaN as 0)
if (isNaN(hours)) hours = 0;
if (isNaN(minutes)) minutes = 0;
// Validate inputs
// Volume must be positive
// Total time must be greater than 0
var totalTimeInHours = hours + (minutes / 60);
if (isNaN(volume) || volume <= 0 || totalTimeInHours <= 0) {
errorMsg.style.display = 'block';
resultContainer.style.display = 'none';
return;
}
// Hide error
errorMsg.style.display = 'none';
// Calculation Logic: Rate = Volume / Time
var flowRate = volume / totalTimeInHours;
// Most pumps allow 1 decimal place, some require whole numbers.
// We will show 1 decimal place for precision.
var formattedRate = flowRate.toFixed(1);
// Display Result
resultDisplay.innerHTML = formattedRate + ' mL/hr';
summaryDisplay.innerHTML = 'To infuse ' + volume + ' mL over ' +
(hours > 0 ? hours + ' hr ' : ") +
(minutes > 0 ? minutes + ' min' : ") +
', set the pump to ' + formattedRate + ' mL/hr.';
resultContainer.style.display = 'block';
}
How to Calculate IV Flow Rate in mL/hr
Calculating the correct intravenous (IV) flow rate is a fundamental skill for nurses and medical professionals. Ensuring accurate infusion rates helps prevent medication errors, fluid overload, and ensures the therapy is delivered effectively over the prescribed duration. This guide explains the formula and process for calculating IV flow rates specifically for electronic infusion pumps, measured in milliliters per hour (mL/hr).
The Formula for IV Flow Rate (mL/hr)
When using an electronic infusion pump, the calculation focuses on volume over time. The standard formula is:
Flow Rate (mL/hr) = Total Volume (mL) ÷ Total Time (hours)
Step-by-Step Calculation Guide
To calculate the rate manually, follow these simple steps:
Identify the Total Volume: This is the amount of fluid ordered by the physician (e.g., 1000 mL of Normal Saline).
Identify the Total Time: This is the duration over which the fluid must be infused (e.g., 8 hours).
Convert Minutes to Hours (if necessary): If the time is given in minutes, divide the minutes by 60 to get the decimal hour equivalent.
Divide: Divide the volume by the time in hours.
Example Calculation 1 (Hours)
Order: Infuse 1000 mL of D5W over 8 hours.
Math: 1000 mL ÷ 8 hr = 125 mL/hr.
Setting: You would set the IV pump to 125.
Example Calculation 2 (Minutes)
Order: Infuse 100 mL of Antibiotic over 30 minutes.
Step 1 (Convert Time): 30 min ÷ 60 = 0.5 hours.
Step 2 (Divide): 100 mL ÷ 0.5 hr = 200 mL/hr.
Setting: Even though the infusion only takes 30 minutes, the pump runs at a speed of 200 mL per hour.
Why is mL/hr Different from gtt/min?
It is crucial to distinguish between calculating for an electronic pump (mL/hr) and gravity flow (gtt/min).
mL/hr (Milliliters per Hour): Used for electronic volumetric pumps. The machine pushes fluid at a specific programmed speed.
gtt/min (Drops per Minute): Used for manual gravity drips. This requires knowing the "drop factor" of the tubing (e.g., 10, 15, 20, or 60 gtt/mL) and involves counting physical drops in the drip chamber.
Clinical Tips for Accuracy
Rounding: Most modern IV pumps can be set to the tenth of a milliliter (e.g., 83.3 mL/hr), but older pumps may require rounding to the nearest whole number. Always follow your facility's policy.
Double Check: Always verify your calculation. If an answer seems unreasonably high or low (e.g., 1000 mL/hr for a maintenance fluid), recalculate and check the order.
Volume To Be Infused (VTBI): When programming the pump, ensure the VTBI matches the bag volume to prevent the line from running dry.