eGFR Calculator — Estimated Kidney Function
Estimate your kidney function (eGFR) from your creatinine level, age and sex using the CKD-EPI 2021 equation used in clinical practice worldwide.
What is eGFR?
Estimated glomerular filtration rate (eGFR) is a measure of how well your kidneys are filtering waste from your blood. The glomeruli are tiny filters in your kidneys, and the GFR reflects how much blood they clean per minute. Because measuring GFR directly is complex, doctors estimate it from a blood test for creatinine — a waste product of muscle activity — combined with your age and sex. eGFR is one of the main tools used to detect and monitor chronic kidney disease.
How eGFR is calculated
This calculator uses the CKD-EPI 2021 creatinine equation, the current international standard. It estimates GFR from your serum creatinine level, age and sex. Unlike older equations, the 2021 version does not adjust for race, reflecting updated clinical guidance. The result is expressed in millilitres per minute per 1.73 square metres of body surface area. A higher number means better kidney function; a normal eGFR for a healthy young adult is usually around 90 to 120.
Understanding kidney disease stages
Chronic kidney disease is staged by eGFR. A value of 90 or above (G1) is normal, 60 to 89 (G2) is mildly reduced, 45 to 59 (G3a) and 30 to 44 (G3b) are moderately reduced, 15 to 29 (G4) is severely reduced, and below 15 (G5) indicates kidney failure. Importantly, a mildly reduced eGFR alone is not necessarily kidney disease — especially in older adults, where some decline is normal — unless there are other signs of kidney damage such as protein in the urine.
What your result means
A single eGFR value is a snapshot and can be affected by hydration, recent meals, muscle mass and certain medications. It should always be interpreted by a doctor, ideally with a repeat test and a urine test for protein. If your eGFR is reduced, do not panic — your doctor will determine whether it reflects a real, ongoing issue and what, if anything, needs to be done. This calculator is for educational understanding and does not replace medical assessment.
Frequently Asked Questions
A normal eGFR for a healthy adult is generally 90 or above, expressed in mL/min/1.73m². Values naturally decline somewhat with age. An eGFR between 60 and 89 can be normal if there are no other signs of kidney damage. Below 60 for three months or more may indicate chronic kidney disease.
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Sources & References
- 1.Inker LA, et al.. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race (CKD-EPI 2021). NEJM.
- 2.Kidney Disease: Improving Global Outcomes (KDIGO). Clinical Practice Guideline for the Evaluation and Management of CKD.
- 3.National Kidney Foundation. Estimated Glomerular Filtration Rate (eGFR).
LifeCheckIQ content is based on peer-reviewed research, recognised clinical guidelines, and authoritative medical sources, and is reviewed by Deborah Adotso, General Nurse, for clinical accuracy.
Medical Disclaimer: This tool is for informational and educational purposes only. Results are not a medical diagnosis. Always consult a qualified healthcare professional for medical advice, diagnosis, or treatment. In an emergency, call your local emergency number or visit the nearest hospital immediately.