What is the CKD-EPI 2021 equation?

It's the current standard race-free equation for eGFR, published by Inker and colleagues in NEJM in 2021. It replaced the 2009 CKD-EPI equation that included a race coefficient — a coefficient the medical community concluded was scientifically and ethically problematic. The 2021 equation is endorsed by the National Kidney Foundation and the American Society of Nephrology.

Why does this calculator not ask for race?

Because the CKD-EPI 2021 equation explicitly removed the race coefficient. Calculators that still ask for race are using the obsolete 2009 equation. Race is a social construct, not a biological filter for kidney function, and modern equations should not depend on it.

What does my CKD stage mean?

Stage G1 (eGFR ≥90) is normal or high. G2 (60–89) is a mild decrease, often without consequences. G3a (45–59) and G3b (30–44) are moderate disease — most patients are managed by primary care or nephrology. G4 (15–29) is severe disease that needs nephrology care and planning for renal replacement therapy. G5 (<15) is kidney failure, requiring dialysis or transplant.

Does a low eGFR mean I have kidney disease?

Not necessarily. eGFR can drop transiently with dehydration, certain medications (NSAIDs, ACE inhibitors), or acute illness. Chronic kidney disease is defined by eGFR below 60 for at least three months, or by other markers like persistent albuminuria.

How accurate is creatinine-based eGFR?

Within roughly ±20% for most people. Accuracy decreases at extremes of muscle mass — body builders may have falsely low eGFR (high creatinine from muscle), and people with low muscle mass may have falsely high eGFR. In those cases, your nephrologist may order a cystatin C-based eGFR or a 24-hour urine collection for confirmation.

What can I do if my eGFR is low?

Talk to your doctor. The fundamentals — controlling blood pressure (especially with ACE inhibitors or ARBs), managing diabetes, avoiding NSAIDs, staying hydrated, and treating proteinuria — slow CKD progression substantially. Diet changes (sodium, protein, potassium, phosphorus) are tailored to the stage and ideally guided by a renal dietitian.

eGFR Calculator — CKD-EPI 2021

eGFR Calculator

CKD-EPI 2021 race-free equation · Kidney function staging

Implements a published clinical formula — see citation

Maintained by TheHealthTools team. Not medical advice.

This calculator uses the 2021 CKD-EPI race-free equation, endorsed by the National Kidney Foundation and the American Society of Nephrology. The 2009 equation that included a race coefficient is no longer recommended.

Serum creatinine (mg/dL)

Age (years)

Sex assigned at birth

The CKD-EPI 2021 equation uses sex (not race) as a covariate because creatinine production differs slightly with muscle mass distribution.

KDIGO 2012 CKD Staging

Stage	eGFR (mL/min/1.73m²)	Description
G1	≥ 90	Normal or high
G2	60 – 89	Mildly decreased
G3a	45 – 59	Mildly to moderately decreased
G3b	30 – 44	Moderately to severely decreased
G4	15 – 29	Severely decreased
G5	< 15	Kidney failure

Stage

eGFR (mL/min/1.73m²)

Description

≥ 90

Normal or high

60 – 89

Mildly decreased

G3a

45 – 59

Mildly to moderately decreased

G3b

30 – 44

Moderately to severely decreased

15 – 29

Severely decreased

< 15

Kidney failure

Why the equation changed in 2021

The original CKD-EPI equation, published in 2009, included a multiplier of 1.159 for patients reported as Black. The justification at the time was statistical: Black participants in the development dataset had slightly higher creatinine on average, presumed to reflect higher muscle mass. The consequence was that Black patients were assigned a higher eGFR for the same creatinine value, which often delayed referral for nephrology care, transplant listing, and medication adjustments.

In 2021, a multidisciplinary task force — the NKF-ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease — recommended replacing the 2009 equation with a race-free version. The new equation, published by Inker and colleagues in NEJM, performs comparably well across populations without using race as an input. It is now the standard recommendation across US clinical labs and is endorsed by both the National Kidney Foundation and the American Society of Nephrology.

Limits of any creatinine-based eGFR

Creatinine is produced by muscle and cleared by the kidneys, so anything that disturbs the relationship between muscle mass and kidney function will throw the estimate off. Body builders may have falsely low eGFR; people with very low muscle mass (e.g., cachexia, paralysis) may have falsely high eGFR. In those cases your nephrologist may order a cystatin C-based eGFR (which uses a different filtered marker) or a 24-hour urine collection.

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(19):1737-1749.

Frequently asked questions

Estimated glomerular filtration rate is a calculated estimate of how much blood your kidneys filter every minute. It's the most useful single number for assessing kidney function. Above 90 is normal; below 60 for three months or longer defines chronic kidney disease.