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GFR Calculator (eGFR, CKD-EPI 2021)

This GFR calculator estimates the glomerular filtration rate (eGFR) from serum creatinine, age and sex with the 2021 CKD-EPI equation. Example: a 50-year-old man with a creatinine of 1.0 mg/dL has an eGFR of 92 mL/min/1.73 m² (stage G1).

Example: Sex: male · Age 50 years · Creatinine unit: mg/dL · Serum creatinine in mg/dL 1 mg/dL → Result: eGFR = 92 mL/min/1.73 m² · stage G1 (normal or high). Source: Inker LA, Eneanya ND, Coresh J, et al. New Creatinine- and Cystatin C–Based Equations to Estimate GFR without Race. N Engl J Med 2021;385:1737–1749 (CKD-EPI-Kreatinin-Gleichung 2021). Updated: .

years
The equation applies to adults aged 18 and over.
mg/dL
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Result

Result
eGFR = 92 mL/min/1.73 m² · stage G1 (normal or high)
KDIGO GFR categories
CategoryeGFR (mL/min/1.73 m²)Kidney function
→ G1≥ 90normal or high
G260–89mildly decreased
G3a45–59mildly to moderately decreased
G3b30–44moderately to severely decreased
G415–29severely decreased
G5< 15kidney failure
Working
  • eGFR = 142 × (1 ÷ 0.9)^-1.200 × 0.9938^50 = 91.69 mL/min/1.73 m².
  • Rounded to 92 → GFR category G1: normal or high.
An estimate from the CKD-EPI 2021 equation for adults – it does not replace a medical assessment. Under KDIGO, chronic kidney disease requires abnormalities that persist for more than three months. The estimate is unreliable in acute kidney injury, in pregnancy and with very unusual muscle mass.

How it is calculated

eGFR is the glomerular filtration rate estimated from a blood test – a measure of how much blood the kidneys filter per minute. It is rarely measured directly; laboratories calculate it from serum creatinine instead. Since 2021 the standard has been the CKD-EPI creatinine equation without a race coefficient (Inker et al., New England Journal of Medicine).

Formula

eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × 1.012 (if female). Scr is serum creatinine in mg/dL; κ is 0.7 for women and 0.9 for men, and α is −0.241 for women and −0.302 for men. Values in µmol/L are first divided by 88.4. The result is normalised to a body surface area of 1.73 m².

Worked example

Man, 50 years old, creatinine 1.0 mg/dL: Scr/κ = 1 ÷ 0.9 = 1.111, which is above 1. eGFR = 142 × 1.111^−1.200 × 0.9938^50 = 142 × 0.8812 × 0.7327 = 91.69, rounded to 92 – stage G1. A woman of the same age with the same creatinine comes to 69 (G2), because κ is 0.7 for her.

Stages G1 to G5

KDIGO sorts GFR into six categories: G1 at 90 or above, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29 and G5 below 15 mL/min/1.73 m². G1 and G2 only count as kidney disease when there are additional markers of kidney damage, such as protein in the urine.

Frequently asked questions

What is a normal GFR?

KDIGO calls 90 mL/min/1.73 m² or more “normal or high” (G1). Values of 60 to 89 are mildly decreased and, without other signs of kidney damage, do not count as kidney disease.

Why is there no race factor in the formula?

The 2021 CKD-EPI equation was deliberately developed without race. It replaces the 2009 version, which included such a coefficient.

How do I convert µmol/L to mg/dL?

Divide by 88.4: 150 µmol/L equals 1.70 mg/dL. The calculator does this for you when you switch the unit.

Does eGFR fall with age?

Yes. For the same creatinine, the factor 0.9938^age lowers the result by roughly 0.6 percent for each year of age.

Sources and legal basis

As of: · Editorial policy

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