Calculate estimated GFR (eGFR) to assess kidney function using the CKD-EPI equation. Includes CKD staging used in Australian nephrology practice.
eGFR (estimated glomerular filtration rate) is a measure of how well your kidneys filter waste from your blood, shown in mL/min/1.73m². It is estimated from a blood creatinine test along with your age and sex, using equations like CKD-EPI. A normal eGFR is generally above 90; lower values may indicate reduced kidney function and are interpreted by a doctor.
⚕️ Medical Notice: This calculator provides an estimate only. eGFR must be interpreted by a qualified clinician alongside clinical history, urine tests, and blood pressure. Consult your GP or nephrologist for medical advice.
| Parameter | Value |
|---|
eGFR is calculated from your blood creatinine level, age and sex. The CKD-EPI 2021 equation is the current standard; MDRD is an older equation still sometimes seen.
Kidney function is grouped into stages by eGFR. These categories are for general understanding — only a doctor can diagnose chronic kidney disease, which also requires other findings.
| Stage | eGFR (mL/min/1.73m²) | General Meaning |
|---|---|---|
| G1 | 90 or above | Normal kidney function |
| G2 | 60–89 | Mildly reduced |
| G3a | 45–59 | Mild–moderate reduction |
| G3b | 30–44 | Moderate–severe reduction |
| G4 | 15–29 | Severely reduced |
| G5 | Under 15 | Kidney failure |
Both equations estimate GFR from creatinine, but CKD-EPI is more accurate, especially at higher (near-normal) GFR levels, and is now recommended.
| Feature | CKD-EPI (2021) | MDRD |
|---|---|---|
| Status | Current recommended standard | Older equation |
| Accuracy near normal GFR | More accurate | Less accurate above 60 |
| Uses a race factor? | No (2021 race-free version) | Original versions did |
| Best for | General clinical use today | Historical comparison |
Several everyday factors influence creatinine and therefore eGFR, which is why one reading is not the whole picture:
| Stage | eGFR (mL/min/1.73m²) | Description |
|---|---|---|
| G1 | ≥ 90 | Normal or high (if markers of kidney damage present) |
| G2 | 60–89 | Mildly decreased |
| G3a | 45–59 | Mildly to moderately decreased |
| G3b | 30–44 | Moderately to severely decreased |
| G4 | 15–29 | Severely decreased |
| G5 | < 15 | Kidney failure — renal replacement therapy |
Source: Kidney Health Australia. In Australia, eGFR is routinely reported by laboratories for all creatinine results in patients ≥18 years.
Glomerular Filtration Rate (GFR) measures how well your kidneys filter waste products from the blood — specifically the volume of blood filtered per minute per 1.73 m² of body surface area (normalised for adult body size). It is the primary measure of kidney function used in clinical practice. A higher GFR indicates better kidney function; a declining GFR indicates kidney disease progression.
| eGFR (mL/min/1.73 m²) | Stage | Kidney Function | Typical Management |
|---|---|---|---|
| 90 or above | G1 (with markers of damage) | Normal or high | Monitor if markers present; none needed if no markers |
| 60–89 | G2 (with markers of damage) | Mildly decreased | Monitor; manage risk factors (BP, diabetes) |
| 45–59 | G3a | Mildly to moderately decreased | GP management; nephrology referral if progressing |
| 30–44 | G3b | Moderately to severely decreased | Nephrology involvement; lifestyle and medication management |
| 15–29 | G4 | Severely decreased | Prepare for kidney replacement therapy |
| Under 15 | G5 (kidney failure) | Kidney failure | Dialysis or kidney transplant |
The CKD-EPI 2021 equation replaced the 2009 version specifically by removing the race variable (which previously gave higher eGFR estimates for Black individuals). Research showed the race adjustment was not supported by adequate biological evidence and led to underdiagnosis of CKD in Black populations. The 2021 race-free equation is now the recommended standard by Kidney Health Australia and the ASN.
What is a normal GFR reading?
A normal eGFR is 90 mL/min/1.73 m² or above for most adults. eGFR between 60-89 is considered mildly decreased but may be normal for older adults without other kidney disease markers. Chronic Kidney Disease (CKD) is defined as eGFR below 60 mL/min/1.73 m² persisting for 3 or more months, or the presence of kidney damage markers regardless of eGFR.
What is the CKD-EPI equation?
CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) is the formula used to estimate GFR from serum creatinine, age, and sex. The 2021 version (used in this calculator) removed the race adjustment that was present in the 2009 version. It uses constants 141 and 0.9938^age as key multipliers, with different constants depending on whether creatinine is above or below sex-specific thresholds.
What conditions can affect GFR readings?
Many conditions and factors affect creatinine levels and therefore eGFR estimates: high muscle mass (increases creatinine, underestimates GFR), low muscle mass or malnutrition (decreases creatinine, overestimates GFR), recent high protein meals, certain medications (trimethoprim, cimetidine), acute kidney injury, and dehydration. These are reasons why eGFR estimation requires clinical interpretation.
Do I have kidney disease if my GFR is below 60?
A single below-60 eGFR reading does not diagnose CKD. Diagnosis requires eGFR below 60 mL/min/1.73 m² on at least two separate measurements at least 90 days apart, OR evidence of kidney damage (proteinuria, structural abnormalities). Consult your GP who can assess your complete clinical picture, repeat the test at an appropriate interval, and order additional tests if needed.
How is eGFR calculated from creatinine?
eGFR is estimated using an equation that combines your blood creatinine level with your age and sex. The current standard is the CKD-EPI 2021 equation. You enter your creatinine and details, and the calculator estimates your eGFR in mL/min/1.73m². The result should be interpreted by your doctor.
What is a normal eGFR level?
An eGFR of 90 or above is generally considered normal in adults with no other signs of kidney damage. Values gradually decline with age, so a slightly lower figure in an older adult is not always a concern. Your doctor interprets your result in the context of your overall health.
What is the difference between CKD-EPI and MDRD?
Both estimate GFR from creatinine, but CKD-EPI is more accurate, particularly at near-normal GFR levels, and is the current recommended equation. The 2021 CKD-EPI version also removed the previous race adjustment. MDRD is an older equation you may still see in some historical results.
Does a low eGFR mean I have kidney disease?
Not on its own. A single low reading can result from dehydration, a recent high-protein meal, high muscle mass or lab variation. Chronic kidney disease is diagnosed by a doctor using repeated eGFR tests over at least three months, together with other findings such as urine tests.
How can I improve my kidney function?
General kidney-supportive habits include staying well hydrated, managing blood pressure and blood sugar, eating a balanced lower-salt diet, avoiding unnecessary anti-inflammatory painkillers, not smoking, and following your doctor’s advice. Any specific plan should be guided by a healthcare professional based on your situation.
Is this eGFR calculator suitable for children?
Adult equations like CKD-EPI are not valid for children. Paediatric eGFR uses different, child-specific equations (such as the Schwartz formula) that account for a child’s height and growth. For a child’s kidney function, always consult a paediatric healthcare provider rather than an adult calculator.
When should I see a doctor about my eGFR?
See a doctor if your eGFR is below the normal range, has dropped over time, or if you have symptoms like swelling, fatigue, changes in urination, or risk factors such as diabetes or high blood pressure. Only a doctor can interpret your result and advise on any follow-up.