eGFR Calculator (Estimated Glomerular Filtration Rate Calculator)

Use this eGFR Calculator to estimate your kidney function using your serum creatinine level, age, sex, and race (where applicable). Estimated glomerular filtration rate (eGFR) can be calculated using several validated equations. This calculator uses the MDRD (Modification of Diet in Renal Disease) equation, one of the most widely recognised methods for estimating kidney function from a routine blood test.

Your eGFR result helps assess how efficiently your kidneys filter waste from your blood. As it is an estimate, your result should always be interpreted alongside your medical history, laboratory findings, and clinical evaluation by a qualified healthcare professional.

What Is eGFR (Estimated Glomerular Filtration Rate)? 

eGFR (estimated glomerular filtration rate) is an estimate of how well your kidneys filter waste products and excess fluid from your blood. It is one of the most important kidney function tests used to detect, monitor, and stage chronic kidney disease (CKD).

Healthy kidneys continuously filter blood, removing waste products, toxins, and excess fluid while maintaining the body's fluid and electrolyte balance. When kidney function declines, these waste products begin to accumulate in the bloodstream, often without noticeable symptoms during the early stages. 

The eGFR provides an estimate of your kidneys' filtering ability, helping doctors detect kidney disease early, monitor its progression, and guide treatment decisions. 

Doctors use eGFR for:

• Assess overall kidney function
• Detect chronic kidney disease (CKD)
• Monitor changes in kidney function over time
• Determine the stage of CKD
• Guide treatment decisions and long-term kidney care

How Is eGFR Estimated? 

eGFR is estimated using your serum creatinine level together with your age, sex, and other clinical factors. Instead of directly measuring kidney filtration through complex tests, doctors estimate kidney function using validated mathematical equations.

The true glomerular filtration rate (GFR) can be measured using specialised methods such as 24-hour urine collection or isotope clearance studies, but these tests are time-consuming and are not routinely performed. For everyday clinical practice, eGFR provides a practical and reliable estimate of kidney function from a simple blood test.

This calculator uses the MDRD (Modification of Diet in Renal Disease) equation, which estimates kidney function using:

Serum creatinine is a waste product produced during normal muscle activity and removed from the body by healthy kidneys. As kidney function declines, serum creatinine levels generally increase, while eGFR decreases. This inverse relationship makes serum creatinine one of the most important markers used to estimate kidney function.

However, serum creatinine alone cannot accurately determine kidney function, as its levels are also influenced by factors such as age, sex, muscle mass, and ethnicity. The MDRD equation accounts for these factors to provide a more accurate estimate of glomerular filtration rate (eGFR) than serum creatinine alone.

While many laboratories now use the CKD-EPI equation, the MDRD equation remains a recognised and validated method for estimating kidney function, particularly in adults with chronic kidney disease.

What Is a Normal eGFR?

A normal eGFR for most healthy adults is 90 mL/min/1.73 m² or higher, although eGFR naturally declines with age.

Healthy adults typically have an eGFR close to 100 mL/min/1.73 m², but normal values vary depending on age, sex, muscle mass, and overall health. As part of the normal ageing process, kidney filtration gradually decreases over time, so a slightly lower eGFR in older adults does not always indicate kidney disease.

An eGFR above 90 mL/min/1.73 m² is generally considered normal when there are no other signs of kidney damage, such as protein in the urine or abnormal kidney imaging.

Age Group	Average eGFR (mL/min/1.73 m²)
20–29 years	116
30–39 years	107
40–49 years	99
50–59 years	93
60–69 years	85
70+ years	75

Historically, healthy women have been observed to have slightly lower average eGFR values than men due to differences in muscle mass and serum creatinine levels.

A normal eGFR should always be interpreted alongside urine tests, medical history, symptoms, and other clinical findings, as a normal eGFR alone does not completely rule out kidney disease.

What Do Your eGFR Results Mean? Understanding eGFR Levels and CKD Stages 

Your eGFR level indicates how efficiently your kidneys filter waste from your blood and helps doctors determine the stage of chronic kidney disease (CKD), if present. 

eGFR (mL/min/1.73 m²)	CKD Stage	Interpretation
90 or above	Stage 1*	Normal or high kidney function
60–89	Stage 2	Mildly reduced kidney function
45–59	Stage 3A	Mild to moderate loss of kidney function
30–44	Stage 3B	Moderate to severe loss of kidney function
15–29	Stage 4	Severely reduced kidney function
Below 15	Stage 5	Kidney failure

Stage 1 CKD is diagnosed only when there is evidence of kidney damage, such as protein in the urine (albuminuria), abnormal kidney imaging, or other markers of kidney disease, despite a normal eGFR.

A single abnormal eGFR result does not necessarily mean you have chronic kidney disease. Doctors generally diagnose CKD only if reduced eGFR or other markers of kidney damage persist for three months or longer.

What Should You Do If Your eGFR Is Low? 

A low eGFR does not always mean permanent kidney disease. It may be caused by chronic kidney disease, temporary medical conditions, or factors that affect kidney filtration. A single low result should always be evaluated by a healthcare professional and may require repeat testing to confirm whether the change is temporary or persistent. 

Common causes of a low eGFR include:

Your doctor may recommend repeat eGFR testing, urine analysis, blood pressure assessment, kidney imaging, or other investigations to determine the underlying cause. 

Can eGFR Improve? 

Yes, eGFR may improve if the underlying cause is temporary or treatable. Conditions such as dehydration, certain medications, or acute illnesses can temporarily reduce kidney filtration, and eGFR may improve once these conditions are managed.

If reduced eGFR is caused by chronic kidney disease, treatment focuses on slowing disease progression, preserving remaining kidney filtration, reducing complications, and protecting long-term kidney health.

Managing blood pressure, controlling diabetes, following a kidney-friendly diet, staying physically active, avoiding smoking, and attending regular medical follow-up can help protect kidney health over time.

When should you see a nephrologist?

You should consult a nephrologist if:

Early evaluation by a kidney specialist can help identify the underlying cause, prevent further kidney damage, and provide timely treatment.

Concerned about your eGFR result? Book an appointment with Dr. Kamal Kiran Mukkavilli for a comprehensive kidney evaluation and personalised treatment plan.