About the eGFR Calculator
Glomerular filtration rate (GFR) measures how much blood your kidneys filter each minute and is the main number used to judge kidney function. Measuring it directly is complicated, so labs report an estimated GFR (eGFR) calculated from a blood creatinine level. This eGFR calculator uses the 2021 CKD-EPI creatinine equation, the version recommended by the US National Kidney Foundation and the American Society of Nephrology, which no longer includes a race coefficient.
Enter your serum creatinine in mg/dL (US) or µmol/L (most other countries), your age and your sex to get eGFR in mL/min/1.73 m² and the matching KDIGO G-stage from G1 (normal) to G5 (kidney failure). The chart shows how the same creatinine level would translate to eGFR at different ages.
The equation is validated for adults aged 18 and over with stable kidney function. It is less reliable in pregnancy, acute kidney injury, very high or low muscle mass, amputations or special diets. Chronic kidney disease is only diagnosed when a reduced eGFR or kidney damage persists for at least three months.
With the default inputs, the egfr is 92 mL/min/1.73 m². Change any value above to recalculate instantly.
How to use the egfr calculator
- 1Find your serum creatinine on a recent blood test report.
- 2Enter the value and choose mg/dL or µmol/L to match the report.
- 3Enter your age and sex.
- 4Read your eGFR and KDIGO G-stage.
- 5Discuss results below 60, or any change over time, with your doctor.
Formula and method
The 2021 CKD-EPI creatinine equation (Inker et al., New England Journal of Medicine) was refitted without a race term. κ is 0.7 for women and 0.9 for men, and α is −0.241 for women and −0.302 for men, so the curve bends at a creatinine of 0.7 or 0.9 mg/dL. Above that point eGFR falls steeply as creatinine rises; below it the effect is gentler. The age term lowers eGFR by about 0.6% per year.
Creatinine in µmol/L is converted to mg/dL by dividing by 88.42. The result is normalised to a body surface area of 1.73 m², the average adult size, which is how labs report it. The G-stage follows the KDIGO classification.
- Scr
- Serum creatinine, mg/dL
- κ
- 0.7 (female) or 0.9 (male)
- α
- −0.241 (female) or −0.302 (male)
- Age
- Age in years
Worked examples
50-year-old man, creatinine 1.0 mg/dL
For a man κ = 0.9, so Scr/κ = 1.111. The max term is 1.111^−1.2 ≈ 0.881 and the age term 0.9938^50 ≈ 0.733. 142 × 0.881 × 0.733 ≈ 92 mL/min/1.73 m², stage G1.
65-year-old woman, creatinine 1.2 mg/dL
For a woman κ = 0.7, so Scr/κ = 1.714 and the max term is 1.714^−1.2 ≈ 0.524. With the age term 0.9938^65 ≈ 0.668 and the 1.012 female factor, eGFR ≈ 50, which is stage G3a.
35-year-old woman, creatinine 62 µmol/L
62 µmol/L ÷ 88.42 ≈ 0.70 mg/dL, almost exactly κ for women. eGFR ≈ 142 × 0.9938^35 × 1.012 ≈ 115 mL/min/1.73 m², normal kidney function.
Frequently asked questions
What is a normal eGFR?+
An eGFR of 90 or above is normal for young adults, and 60–89 is common in older adults and is not considered kidney disease unless there are other signs of damage such as protein in the urine. Below 60 for three months or more indicates chronic kidney disease.
Why was race removed from the eGFR equation?+
The 2009 CKD-EPI equation multiplied eGFR by 1.159 for Black patients, which could delay diagnosis and referral. In 2021 a joint NKF–ASN task force recommended the refitted CKD-EPI equation without a race coefficient, and most US labs have adopted it.
Can I improve my eGFR?+
Short-term changes come from hydration, recent meat intake, creatine supplements and intense exercise, which raise creatinine. Long-term kidney protection focuses on controlling blood pressure and blood sugar, avoiding regular NSAID use, not smoking and following your doctor’s advice on medications.
What is the difference between eGFR and creatinine clearance?+
eGFR estimates filtration normalised to 1.73 m² of body surface, and is used for staging kidney disease. Creatinine clearance (Cockcroft-Gault) estimates filtration in mL/min using body weight and is still used to dose some drugs.
Does muscle mass affect eGFR?+
Yes. Creatinine comes from muscle, so very muscular people can have a falsely low eGFR and people with low muscle mass a falsely high one. A cystatin C test, or an equation combining creatinine and cystatin C, can give a more accurate estimate in those cases.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.