.flow-rate-calculator-container {
font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
color: #333;
line-height: 1.6;
}
.calc-wrapper {
background-color: #f8fbfd;
border: 1px solid #e1e8ed;
border-radius: 8px;
padding: 30px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
margin-bottom: 40px;
}
.calc-title {
text-align: center;
color: #0056b3;
margin-bottom: 25px;
font-size: 24px;
font-weight: 700;
}
.form-group {
margin-bottom: 20px;
}
.form-row {
display: flex;
gap: 20px;
flex-wrap: wrap;
}
.col-half {
flex: 1;
min-width: 200px;
}
label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #444;
}
input[type="number"] {
width: 100%;
padding: 12px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
input[type="number"]:focus {
border-color: #0056b3;
outline: none;
box-shadow: 0 0 0 2px rgba(0,86,179,0.2);
}
.calc-btn {
display: block;
width: 100%;
background-color: #0056b3;
color: white;
padding: 15px;
border: none;
border-radius: 4px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.3s;
margin-top: 10px;
}
.calc-btn:hover {
background-color: #004494;
}
.result-box {
margin-top: 25px;
padding: 20px;
background-color: #e8f4fd;
border-left: 5px solid #0056b3;
border-radius: 4px;
display: none;
}
.result-label {
font-size: 14px;
color: #555;
text-transform: uppercase;
letter-spacing: 1px;
}
.result-value {
font-size: 32px;
font-weight: bold;
color: #0056b3;
margin-top: 5px;
}
.error-msg {
color: #d32f2f;
font-size: 14px;
margin-top: 5px;
display: none;
}
.article-content h2 {
color: #2c3e50;
margin-top: 30px;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
}
.article-content h3 {
color: #34495e;
margin-top: 20px;
}
.article-content p {
margin-bottom: 15px;
}
.formula-box {
background: #f9f9f9;
border-left: 4px solid #7f8c8d;
padding: 15px;
font-family: 'Courier New', monospace;
margin: 20px 0;
}
function calculateFlowRate() {
// Get inputs using var
var volumeInput = document.getElementById("totalVolume");
var hoursInput = document.getElementById("durationHours");
var minutesInput = document.getElementById("durationMinutes");
var resultBox = document.getElementById("resultBox");
var resultText = document.getElementById("flowRateResult");
var errorMsg = document.getElementById("errorMessage");
var displayVol = document.getElementById("displayVolume");
var displayTime = document.getElementById("displayTime");
// Parse values
var volume = parseFloat(volumeInput.value);
var hours = parseFloat(hoursInput.value);
var minutes = parseFloat(minutesInput.value);
// Handle NaN inputs (treat empty fields as 0)
if (isNaN(hours)) hours = 0;
if (isNaN(minutes)) minutes = 0;
// Validation
if (isNaN(volume) || volume <= 0) {
errorMsg.style.display = "block";
resultBox.style.display = "none";
errorMsg.innerText = "Please enter a valid total volume in mL.";
return;
}
// Calculate total time in hours
var totalTimeInHours = hours + (minutes / 60);
if (totalTimeInHours <= 0) {
errorMsg.style.display = "block";
resultBox.style.display = "none";
errorMsg.innerText = "Total duration must be greater than zero.";
return;
}
// Hide error if valid
errorMsg.style.display = "none";
// Calculation Logic: Rate = Volume / Time
var flowRate = volume / totalTimeInHours;
// Rounding to 1 decimal place (standard for IV pumps)
var formattedRate = Math.round(flowRate * 10) / 10;
// Display Results
resultBox.style.display = "block";
resultText.innerHTML = formattedRate + " mL/hr";
displayVol.innerHTML = volume;
displayTime.innerHTML = totalTimeInHours.toFixed(2);
}
How to Calculate Flow Rate in mL per Hour
Calculating the flow rate in milliliters per hour (mL/hr) is a fundamental skill in nursing and clinical practice. It ensures that patients receive Intravenous (IV) fluids or medications at the correct speed to maintain therapeutic levels and prevent fluid overload. While electronic infusion pumps handle the mechanics, understanding the manual calculation is critical for verification and settings where pumps are unavailable.
The Flow Rate Formula
The standard formula to calculate the flow rate for an electronic infusion pump is straightforward. You are solving for the volume of fluid to be infused over a specific period of time.
Flow Rate (mL/hr) = Total Volume (mL) ÷ Total Time (hours)
If the time is provided in minutes, you must convert it to hours first by dividing the minutes by 60.
Step-by-Step Calculation Guide
- Identify the Total Volume: Determine the total amount of fluid ordered by the physician (e.g., 1000 mL of Normal Saline).
- Identify the Duration: Determine the total time over which the fluid must be infused (e.g., 8 hours).
- Convert Time if Necessary: If the order is in minutes (e.g., 30 minutes), convert to hours: 30 ÷ 60 = 0.5 hours.
- Divide Volume by Time: Perform the division to find the rate.
Practical Examples
Example 1: Standard Hydration
Order: Infuse 1,000 mL of D5W over 8 hours.
- Volume = 1,000 mL
- Time = 8 hours
- Calculation: 1,000 ÷ 8 = 125 mL/hr
Example 2: Antibiotic Infusion
Order: Infuse 100 mL of Vancomycin over 30 minutes.
- Volume = 100 mL
- Time = 30 minutes
- Convert Time: 30 min ÷ 60 = 0.5 hours
- Calculation: 100 ÷ 0.5 = 200 mL/hr
Why Precision Matters
Incorrect flow rates can lead to serious complications. A rate that is too slow may result in inadequate hydration or sub-therapeutic drug levels. Conversely, a rate that is too fast can cause fluid volume overload, congestive heart failure, or phlebitis. Always double-check your calculations and verify the pump settings against the physician's order.
Manual Gravity Drip vs. Infusion Pump
This calculator determines the setting for an electronic infusion pump, which measures in mL/hr. If you are using manual gravity tubing, you will need to calculate the drop rate (gtt/min), which involves the tubing's drop factor (e.g., 10, 15, or 60 gtt/mL). The formula for drop rate is:
(Total Volume in mL × Drop Factor) ÷ Time in Minutes = Drops per Minute (gtt/min)