GFR Calculator (CKD-EPI 2021)
Calculate estimated glomerular filtration rate using the CKD-EPI 2021 creatinine equation. Race-free formula recommended by KDIGO guidelines.
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Valid for adults ≥18 years
Standard serum creatinine measurement
About CKD-EPI 2021
This calculator uses the race-free CKD-EPI 2021 equation, recommended by KDIGO guidelines. The equation was updated to remove the race coefficient.
Estimated GFR
Enter values to calculate
About This Calculator
The CKD-EPI 2021 equation estimates glomerular filtration rate (GFR) from serum creatinine. This updated equation removes the race coefficient, providing a single equation for all patients. It is recommended by KDIGO (Kidney Disease: Improving Global Outcomes) for routine clinical use.
Formula
eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^-1.200 × 0.9938^Age × (1.012 if female)Where: • Scr = serum creatinine (mg/dL) • κ = 0.7 (females) or 0.9 (males) • α = -0.241 (females) or -0.302 (males) • min = minimum of Scr/κ or 1 • max = maximum of Scr/κ or 1
Clinical Considerations
- •Not validated for acute kidney injury (AKI) - use clinical judgment
- •Less accurate at extremes of body size or muscle mass
- •Should be used with albuminuria for complete CKD assessment
Limitations
- •Valid for adults ≥18 years only
- •Requires stable serum creatinine (not applicable in AKI)
- •May be inaccurate with extreme muscle mass
- •Does not account for cystatin C
Interpretation Guide
| Range | Classification | Recommendation |
|---|---|---|
| 90-+ | G1 - Normal or High | No action needed if no other markers of kidney damage |
| 60-89 | G2 - Mildly Decreased | Monitor annually; assess cardiovascular risk |
| 45-59 | G3a - Mildly to Moderately Decreased | Monitor every 6 months; refer to nephrology if progressive |
| 30-44 | G3b - Moderately to Severely Decreased | Monitor every 3-6 months; nephrology referral recommended |
| 15-29 | G4 - Severely Decreased | Nephrology management; prepare for renal replacement therapy |
| <-14 | G5 - Kidney Failure | Dialysis or transplant planning indicated |
Frequently Asked Questions
What is GFR?
GFR (Glomerular Filtration Rate) measures how well your kidneys filter blood. It estimates how much blood passes through the glomeruli (tiny filters in the kidneys) each minute. A normal GFR is above 90 mL/min/1.73m².
Why was the race coefficient removed from the CKD-EPI equation?
The 2021 CKD-EPI equation removed the race coefficient based on evidence that race is a social construct without biological basis for kidney function estimation. The new equation performs similarly across racial groups and eliminates potential for racial bias in clinical care.
When should I use GFR vs. Creatinine Clearance?
eGFR is preferred for routine clinical assessment and CKD staging. Creatinine Clearance (Cockcroft-Gault) is still used for drug dosing adjustments, particularly for medications with narrow therapeutic windows.
What are the limitations of eGFR?
eGFR may be inaccurate in patients with: extreme body size, unusual muscle mass (bodybuilders, amputees), acute kidney injury, pregnancy, or certain diets (vegetarian, creatine supplements). In these cases, measured GFR or cystatin C-based equations may be more appropriate.
How is CKD staged?
CKD is staged by GFR category (G1-G5) and albuminuria category (A1-A3). Stage G1 is ≥90 with kidney damage markers, G2 is 60-89, G3a is 45-59, G3b is 30-44, G4 is 15-29, and G5 is <15 mL/min/1.73m².
References
1. 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. doi: 10.1056/NEJMoa2102953
View Source →2. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of CKD. Kidney Int. 2024
View Source →Last updated: 2024-12-18
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