GFR Calculator
Estimate your Glomerular Filtration Rate (eGFR) using the race-free 2021 CKD-EPI creatinine equation. Enter serum creatinine (mg/dL), age, and biological sex — adults 18 and older.
How It's Calculated
Formula
\text{eGFR} = 142 \times \min(S_{cr}/k, 1)^{\alpha} \times \max(S_{cr}/k, 1)^{-1.200} \times 0.9938^{\text{Age}} \times \text{sex factor}This calculator estimates Glomerular Filtration Rate (eGFR) using the 2021 CKD-EPI creatinine equation, the race-free version currently recommended by NIDDK/NKF guidance for adults. It replaces the earlier 2009 CKD-EPI equation, which included a race coefficient now considered outdated. Serum creatinine (k = 0.7 for women, 0.9 for men), age, and biological sex are combined with fixed published constants to produce an eGFR in mL/min/1.73m². This is an estimate for general informational and educational purposes, based on a published formula — it is not a medical diagnosis, and it is not a substitute for individualized advice from a qualified healthcare provider. This tool reports the eGFR number and equation version only — it does not classify chronic kidney disease (CKD) stage, does not diagnose kidney disease, and is not a substitute for a clinician's interpretation of your lab results in the context of your full medical history. This equation applies to adults age 18 and older.
Worked Examples
Male, age 50, serum creatinine 1.0 mg/dL
- Scr/k = 1.0 / 0.9 = 1.111 (above 1, so the high-ratio exponent branch applies)
- eGFR = 142 x 1^-0.302 x 1.111^-1.200 x 0.9938^50 x 1.0 ≈ 91.7 mL/min/1.73m²
Female, age 50, serum creatinine 1.0 mg/dL
- Scr/k = 1.0 / 0.7 = 1.429 (above 1, high-ratio branch)
- eGFR = 142 x 1^-0.241 x 1.429^-1.200 x 0.9938^50 x 1.012 ≈ 68.6 mL/min/1.73m²
Frequently Asked Questions
Why is there no race input?
This calculator uses the 2021 CKD-EPI creatinine equation, which NIDDK/NKF guidance currently recommends as the race-free standard for adult eGFR estimation. It replaces the earlier 2009 equation that used a race coefficient.
Does this tell me what CKD stage I'm in?
No. This calculator reports the eGFR number, the equation version, and units only. Chronic kidney disease staging depends on more than a single eGFR value and should be interpreted by a qualified healthcare provider.
Can I use this if I'm under 18?
No. The 2021 CKD-EPI creatinine equation used here applies to adults age 18 and older; this calculator does not accept ages below 18.
What units does serum creatinine need to be in?
mg/dL. If your lab result is reported in µmol/L, convert it first (mg/dL = µmol/L / 88.4) before entering it here.