eGFR Calculator (CKD-EPI 2021)

eGFR shows how well your kidneys filter the blood and is expressed in millilitres per minute, adjusted to a standard body surface area of 1.73 m². It is not measured directly but estimated from a simple blood test, serum creatinine, together with your age and sex. The calculator uses the CKD-EPI 2021 formula, currently recommended internationally, which no longer applies any correction based on race.

As a rough guide, under the KDIGO classification, above 90 means normal or high function (G1), 60–89 a mild decrease (G2), 45–59 a mild to moderate decrease (G3a), 30–44 a moderate to severe decrease (G3b), 15–29 a severe decrease (G4), and below 15 kidney failure (G5). It is important to remember that a single value does not make the diagnosis. Chronic kidney disease means changes that persist for at least 3 months, and full staging also takes into account the amount of albumin lost in the urine. The final interpretation rests with your doctor.

Diabetes is one of the most common causes of chronic kidney disease, and kidney damage is painless and gives no warning signs for a long time. This is why guidelines recommend checking eGFR and urinary albumin once a year in people with diabetes. Early detection allows treatments that considerably slow the disease, and some medicines need their dose adjusted when kidney function declines.

The formula assumes an average muscle mass. In people who are very muscular, very underweight, have had an amputation, or are pregnant, the estimate can be misleading. Creatinine also varies with hydration, a diet high in meat, or intense physical exercise in the days before the test. At normal or near-normal values it is less precise than at low values. The result is a guide, not a diagnosis.