GFR Calculator
Estimate your kidney function with precision
GFR Calculator for Adults
Advanced kidney function assessment for patients 18+ years
GFR Calculator for Children
Pediatric kidney function assessment for patients ≤18 years
Calculation Results
Chronic Kidney Disease Stages
| Stage | Description | GFR Range |
|---|---|---|
| Normal | Normal kidney function | 90+ mL/min/1.73 m² |
| Stage 1 | Kidney damage with normal function | 90+ with proteinuria |
| Stage 2 (Mild) | Mild loss of kidney function | 60-89 |
| Stage 3 (Moderate) | Moderate loss of kidney function | 30-59 |
| Stage 4 (Severe) | Severe loss of kidney function | 15-29 |
| Stage 5 (Kidney Failure) | Kidney failure | < 15 |
GFR CALCULATOR
What is Glomerular Filtration Rate (GFR)?
Glomerular Filtration Rate (GFR) is a key indicator of kidney health. It measures how much blood is filtered by the glomeruli — tiny filters in the kidneys — each minute. A higher GFR reflects better kidney function, while a decline in GFR may indicate impaired kidney performance or chronic kidney disease (CKD).
In healthy adults, the average GFR (adjusted for body surface area) typically ranges:
Men (under 40 years): 100–130 mL/min/1.73 m²
Women (under 40 years): 90–120 mL/min/1.73 m²
After the age of 40, GFR naturally decreases by about 1 mL/min per year, reflecting normal aging rather than disease progression.
Population Mean Estimated GFR by Age:
The following table shows average GFR values across different age groups:
| Age (years) | Mean Estimated GFR (mL/min/1.73 m²) |
|---|---|
| 20–29 | 116 |
| 30–39 | 107 |
| 40–49 | 99 |
| 50–59 | 93 |
| 60–69 | 85 |
| 70+ | 75 |
Chronic Kidney Disease (CKD) Stages:
A GFR value above 60 mL/min/1.73 m² is usually considered adequate. However, a significant decline compared to prior tests may indicate early kidney disease. Detecting CKD early is critical, as timely treatment can reduce the risk of dialysis or kidney failure.
| Stage | GFR Value (mL/min/1.73 m²) | Description |
|---|---|---|
| Normal | 90+ (no proteinuria) | Normal kidney function |
| CKD 1 | 90+ with kidney damage | Early kidney disease |
| CKD 2 (Mild) | 60–89 with damage | Mild loss of function |
| CKD 3 (Moderate) | 30–59 | Moderate loss of function |
| CKD 4 (Severe) | 15–29 | Severe kidney damage |
| CKD 5 (Failure) | <15 | Kidney failure (may require dialysis) |
How is GFR Measured?
The most precise way to measure GFR is through inulin clearance, where an injected marker (inulin) is tracked as it passes through the kidneys. While highly accurate, this method requires repeated blood and urine samples, making it impractical for daily clinical use.
Instead, clinicians commonly estimate GFR using serum creatinine-based formulas. Creatinine, a byproduct of muscle metabolism, is filtered by the kidneys, and its concentration in the blood can be used to estimate GFR. However, creatinine levels are influenced by muscle mass, diet, and other factors, meaning results can vary between individuals.
Common Formulas to Estimate GFR:
Several equations are used in practice to provide reliable eGFR (estimated GFR):
MDRD Equation (IDMS-traceable):
GFR = 175 × (Serum Creatinine)^-1.154 × (Age)^-0.203 × (0.742 if female) × (1.212 if Black)CKD-EPI Formula:
More accurate at higher GFR levels and widely recommended for clinical use.Schwartz Formula (for children):
Based on serum creatinine and height, adjusted with an age-appropriate constant.
This GFR Calculator offers a quick way to understand how well your kidneys are working. Use it to estimate your Glomerular Filtration Rate and gain insights into kidney health, but always consult a healthcare professional for accurate diagnosis and treatment.
Related Calculators:
TDEE Calculator, Fat Intake CalculatorExternal Resources:
GFR Calculator on Calculator.net
A normal GFR is typically 90 mL/min/1.73 m² or higher. However, normal ranges vary with age, gender, and body size. A slightly lower GFR may be expected in older adults.
A GFR below 60 mL/min/1.73 m² for three months or more may indicate chronic kidney disease (CKD). You should consult a healthcare professional for further evaluation and management.
While you cannot directly increase GFR, you can protect your kidneys by:
Controlling blood pressure and blood sugar
Eating a kidney-friendly diet (low sodium, balanced protein)
Staying hydrated
Avoiding smoking and excessive alcohol
Following your doctor’s advice on medications
GFR is the exact filtration rate measured in a lab using special markers like inulin. eGFR (estimated GFR) is calculated using blood tests (creatinine levels) and formulas, making it practical for everyday medical use.
Dialysis is usually recommended when GFR falls below 15 mL/min/1.73 m² and symptoms of kidney failure appear. The exact timing depends on overall health, symptoms, and your doctor’s recommendation.