The Estimated Glomerular Filtration Rate (eGFR) is a key indicator of kidney function. It estimates how much blood passes through the glomeruli (the tiny filters in the kidneys) each minute. This calculator uses the CKD-EPI 2021 Creatinine Equation, which is currently recommended by the National Kidney Foundation and does not include race as a variable.
CKD Stages and Interpretation
Stage
eGFR Range (mL/min/1.73m²)
Description
Stage 1
90 or higher
Normal or high kidney function
Stage 2
60 – 89
Mildly decreased kidney function
Stage 3a
45 – 59
Mild to moderately decreased kidney function
Stage 3b
30 – 44
Moderate to severely decreased kidney function
Stage 4
15 – 29
Severely decreased kidney function
Stage 5
Less than 15
Kidney failure (End Stage Renal Disease)
How is eGFR Calculated?
The formula takes into account your serum creatinine level, age, and biological sex. Creatinine is a waste product generated by muscle metabolism. Healthy kidneys filter creatinine out of the blood. If kidney function declines, creatinine levels in the blood rise.
Early detection of kidney disease is crucial because symptoms often do not appear until the later stages. Knowing your eGFR helps doctors:
Diagnose Chronic Kidney Disease (CKD)
Monitor the progression of kidney disease
Adjust dosages of medications that are cleared by the kidneys
Determine when dialysis or a kidney transplant might be necessary
Limitations
While eGFR is a highly useful tool, it is an estimate. It may not be accurate for:
People with extreme muscle mass (bodybuilders or amputees)
Those with acute kidney failure (sudden onset)
Individuals on strict vegetarian diets (affecting creatinine levels)
Pregnant women
Disclaimer: This calculator is for educational purposes only and should not replace professional medical advice. Always consult with a healthcare provider for diagnosis and treatment.
function updatePlaceholder() {
var unit = document.getElementById('unit').value;
var input = document.getElementById('creatinine');
if(unit === 'mgdl') {
input.placeholder = "e.g. 1.2";
} else {
input.placeholder = "e.g. 106";
}
}
function calculateEGFR() {
// Get Inputs
var age = parseFloat(document.getElementById('age').value);
var gender = document.getElementById('gender').value;
var creatRaw = parseFloat(document.getElementById('creatinine').value);
var unit = document.getElementById('unit').value;
// Error Handling
var errorBox = document.getElementById('creat-error');
var resultBox = document.getElementById('result-box');
if (isNaN(age) || age <= 0) {
alert("Please enter a valid age.");
return;
}
if (isNaN(creatRaw) || creatRaw = 90) {
stage = "Stage 1";
desc = "Normal or high kidney function";
color = "#27ae60"; // Green
} else if (egfr >= 60) {
stage = "Stage 2";
desc = "Mildly decreased kidney function";
color = "#8e44ad"; // Purple
} else if (egfr >= 45) {
stage = "Stage 3a";
desc = "Mild to moderately decreased kidney function";
color = "#f39c12"; // Orange
} else if (egfr >= 30) {
stage = "Stage 3b";
desc = "Moderate to severely decreased kidney function";
color = "#d35400"; // Dark Orange
} else if (egfr >= 15) {
stage = "Stage 4";
desc = "Severely decreased kidney function";
color = "#c0392b"; // Red
} else {
stage = "Stage 5";
desc = "Kidney failure";
color = "#7f8c8d"; // Gray/Black
}
// Display Results
resultBox.style.display = 'block';
document.getElementById('egfr-value').innerHTML = egfr + ' mL/min/1.73m²';
var stageElem = document.getElementById('ckd-stage');
stageElem.textContent = stage;
stageElem.style.color = color;
document.getElementById('stage-desc').textContent = desc;
// Scroll to result
resultBox.scrollIntoView({ behavior: 'smooth' });
}