Health

GFR Calculator (eGFR)

Estimate your eGFR with the 2021 race-free CKD-EPI Creatinine equation and see your chronic kidney disease (CKD) stage.

GFR Calculator (eGFR)

Serum Creatinine (mg/dL)

Age (years)

Sex

Method

How this calculator works

eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × (1.012 if female), where κ = 0.7 (female) or 0.9 (male) and α = −0.241 (female) or −0.302 (male).

Enter your serum creatinine in mg/dL, your age in years, and select your sex.
The calculator picks κ (0.7 female, 0.9 male) and α (−0.241 female, −0.302 male).
It computes 142 × min(Scr/κ,1)^α × max(Scr/κ,1)^−1.200 × 0.9938^age, then multiplies by 1.012 for females.
The rounded result in mL/min/1.73m² is matched to its CKD stage.

Examples

Worked examples

Real numbers, end-to-end results.

Female, 55 yrs, creatinine 0.9 mg/dL

≈ 73 mL/min/1.73m² (G2)

Scr/κ = 0.9/0.7 = 1.29, so the max term dominates: 142 × 1 × 1.29^−1.2 × 0.9938^55 × 1.012.

Male, 40 yrs, creatinine 1.1 mg/dL

≈ 82 mL/min/1.73m² (G2)

Scr/κ = 1.1/0.9 = 1.22; the equation applies the −1.200 exponent to the value above 1.

Male, 68 yrs, creatinine 1.6 mg/dL

≈ 46 mL/min/1.73m² (G3a)

Higher creatinine and age push the estimate into the mild-to-moderate reduction range.

Use cases

When to use it

Screening and monitoring chronic kidney disease over time.
Adjusting the dose of drugs cleared by the kidneys.
Assessing kidney function before contrast imaging or surgery.
Tracking the impact of diabetes or high blood pressure on the kidneys.

Disclaimer: This calculator provides estimates for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for decisions affecting your health. Results depend on the accuracy of inputs provided.

FAQ

Frequently asked questions

What is eGFR and what does it measure?

eGFR (estimated glomerular filtration rate) estimates how many milliliters of blood your kidneys filter per minute, standardized to a body surface area of 1.73 m². It is the single most important number for assessing kidney function and staging chronic kidney disease (CKD).

Which equation does this calculator use?

It uses the 2021 CKD-EPI Creatinine equation, the race-free formula recommended by the National Kidney Foundation and ASN. It removed the earlier race coefficient to provide a more equitable estimate, using only serum creatinine, age, and sex.

What is a normal eGFR value?

An eGFR of 90 mL/min/1.73m² or higher is generally considered normal in adults with no other signs of kidney damage. Values decline naturally with age, so a slightly lower number in older adults is not always a sign of disease.

What do the CKD stages mean?

CKD is staged G1 (≥90), G2 (60–89), G3a (45–59), G3b (30–44), G4 (15–29), and G5 (<15). Stages G1 and G2 require evidence of kidney damage (such as protein in urine) to be called CKD, while G3–G5 are defined by the eGFR level itself.

Can I use this instead of a doctor's assessment?

No. This tool is for education and estimation only. A single creatinine reading can be affected by hydration, muscle mass, diet, and medications. Always have kidney function interpreted by a qualified healthcare provider alongside other tests.