Check your IV tubing packaging for the Drop Factor (gtt/mL).
Calculation Results
Flow Rate (Pump):0 mL/hr
Drip Rate (Gravity):0 gtt/min
Drop Interval:0 sec/drop
How to Calculate IV Drip Rate in mL/hr
Calculating the correct intravenous (IV) drip rate is a fundamental skill for nurses, paramedics, and medical professionals. Whether you are setting an electronic infusion pump or manually adjusting a gravity-fed line, accuracy is critical for patient safety.
The Basic Formula for mL/hr
If you are using an electronic infusion pump, the primary setting you need is the flow rate in milliliters per hour (mL/hr). The formula is straightforward:
Rate (mL/hr) = Total Volume (mL) ÷ Total Time (hours)
Example: 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
Calculating Drops Per Minute (gtt/min)
When an infusion pump is not available, you must manually regulate the flow using the roller clamp on the IV tubing. To do this, you need to calculate the drops per minute (gtt/min). This requires knowing the Drop Factor of your tubing set, which is printed on the tubing packaging (measured in drops per mL or gtt/mL).
Flow Rate (gtt/min) = (Total Volume (mL) × Drop Factor) ÷ Time (minutes)
Common drop factors include:
Macrodrip sets: 10, 15, or 20 gtt/mL (used for general infusions).
Microdrip sets: 60 gtt/mL (used for pediatrics or precise medication).
Clinical Relevance and Safety
Incorrect flow rates can lead to complications. An infusion that is too fast may cause fluid overload or medication toxicity, while a rate that is too slow may result in inadequate therapy or dehydration. Always double-check your calculations and verify the drop factor of the specific tubing you are using.
function calculateIVRate() {
// 1. Get Input Elements
var volumeInput = document.getElementById('ivVolume');
var hoursInput = document.getElementById('ivHours');
var minutesInput = document.getElementById('ivMinutes');
var dropFactorInput = document.getElementById('ivDropFactor');
// 2. Get Input Values
var volume = parseFloat(volumeInput.value);
var hours = parseFloat(hoursInput.value);
var minutes = parseFloat(minutesInput.value);
var dropFactor = parseFloat(dropFactorInput.value);
// 3. Reset Errors and Results
document.getElementById('ivVolumeError').style.display = 'none';
document.getElementById('ivTimeError').style.display = 'none';
document.getElementById('ivResult').style.display = 'none';
// 4. Validate Inputs
var isValid = true;
if (isNaN(volume) || volume <= 0) {
document.getElementById('ivVolumeError').style.display = 'block';
isValid = false;
}
// Handle NaN for time inputs (treat empty as 0)
if (isNaN(hours)) hours = 0;
if (isNaN(minutes)) minutes = 0;
var totalHours = hours + (minutes / 60);
var totalMinutes = (hours * 60) + minutes;
if (totalMinutes 0) {
secondsPerDrop = 60 / dropsPerMin;
}
// 6. Display Results
// Rounding: mL/hr usually to 1 decimal, gtt/min to whole number (cannot count partial drops)
document.getElementById('resMlHr').innerText = mlPerHour.toFixed(1);
document.getElementById('resGttMin').innerText = Math.round(dropsPerMin);
// For seconds per drop, show 1 decimal if manageable, or text if too fast
if (secondsPerDrop < 0.5) {
document.getElementById('resSecDrop').innerText = "< 0.5 (Too fast)";
} else {
document.getElementById('resSecDrop').innerText = secondsPerDrop.toFixed(1);
}
document.getElementById('ivResult').style.display = 'block';
}