Calculate infusion rates for medical administration accurately.
10 (Macro)
15 (Macro)
20 (Macro)
60 (Micro)
Flow Rate: mL/hr
Drip Rate: gtt/min
Total Duration: minutes
Understanding IV Rate Calculations
In clinical settings, calculating the correct Intravenous (IV) flow rate is critical for patient safety. Whether you are using an infusion pump or setting a gravity drip, you must determine how much fluid is delivered over a specific period.
Core Formulas for IV Therapy
There are two primary ways to express IV rates: milliliters per hour (mL/hr) and drops per minute (gtt/min).
Flow Rate (mL/hr) = Total Volume (mL) ÷ Total Time (hr)
Drip Rate (gtt/min) = [Total Volume (mL) × Drop Factor (gtt/mL)] ÷ Total Time (min)
Key Terms Explained
Volume (mL): The total amount of fluid or medication ordered (e.g., Normal Saline, D5W).
Drop Factor (gtt/mL): The number of drops it takes to equal 1 mL. This is determined by the administration set. Common sizes are 10, 15, or 20 (macrodrip) and 60 (microdrip).
Flow Rate (mL/hr): Used when setting an electronic infusion pump.
Drip Rate (gtt/min): Used when manually regulating the IV using the roller clamp and a watch.
Practical Example
Scenario: A physician orders 500 mL of 0.9% NS to be infused over 4 hours. You are using a drip set with a drop factor of 15 gtt/mL.
Always double-check calculations with a colleague in high-risk scenarios. Ensure the drop factor on the physical tubing package matches the number used in your calculation. If a rate seems abnormally high or low, re-verify the physician's order before starting the infusion.
function calculateIVRate() {
var volume = parseFloat(document.getElementById('ivVolume').value);
var hours = parseFloat(document.getElementById('ivHours').value) || 0;
var minutes = parseFloat(document.getElementById('ivMinutes').value) || 0;
var dropFactor = parseFloat(document.getElementById('dropFactor').value);
var resultDiv = document.getElementById('ivResult');
if (isNaN(volume) || volume <= 0 || (hours <= 0 && minutes <= 0)) {
alert('Please enter a valid volume and time duration.');
resultDiv.style.display = 'none';
return;
}
var totalMinutes = (hours * 60) + minutes;
var totalHours = totalMinutes / 60;
// Flow Rate calculation (mL/hr)
var flowRate = volume / totalHours;
// Drip Rate calculation (gtt/min)
var dripRate = (volume * dropFactor) / totalMinutes;
// Output results
document.getElementById('resFlowRate').innerText = flowRate.toFixed(2);
document.getElementById('resDripRate').innerText = Math.round(dripRate);
document.getElementById('resTotalTime').innerText = totalMinutes;
resultDiv.style.display = 'block';
}