eGFR Calculator (CKD-EPI 2021 Race-Free)

Estimate your kidney function (glomerular filtration rate) from serum creatinine, age, and sex using the current gold-standard 2021 CKD-EPI race-free equation. See your KDIGO CKD stage instantly.

Serum Creatinine

mg/dL

Age (years)

yrs

Biological Sex

eGFR — mL/min/1.73m²

G1
≥90 G2
60–89 G3a
45–59 G3b
30–44 G4
15–29 G5
<15

CKD Stage --

Clinical interpretation --

Important: A single eGFR result does not diagnose CKD. CKD requires either an eGFR <60 mL/min/1.73m² sustained for ≥3 months, or the presence of kidney damage markers (e.g. albuminuria, abnormal imaging or biopsy). Always discuss your result with your doctor.

What eGFR Estimates

The glomerular filtration rate (GFR) is the volume of fluid filtered from the blood through the kidney's tiny filters — the glomeruli — per minute per 1.73 m² of standardized body surface area. Because measuring true GFR requires injecting exogenous markers (such as inulin or iohexol), clinical practice relies on the estimated GFR (eGFR), calculated from serum creatinine — a waste product of muscle metabolism excreted almost entirely by the kidneys. When kidneys filter less efficiently, creatinine accumulates in the blood; eGFR equations translate that accumulation into an estimate of filtration capacity.

The 2021 CKD-EPI equation (Chronic Kidney Disease Epidemiology Collaboration) is the recommended formula for estimating GFR in adults per KDIGO 2024 guidelines and the current standard in the United States, United Kingdom, and most of Europe. It uses serum creatinine (in mg/dL), age, and biological sex. Unlike earlier equations, it applies no race-based coefficient.

Reference: Inker LA, et al. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385:1737–1749. doi:10.1056/NEJMoa2102953

CKD-EPI 2021 (creatinine, race-free):
eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^Age × (1.012 if female)

κ = 0.7 (female), 0.9 (male)
α = −0.241 (female), −0.302 (male)
Scr = serum creatinine in mg/dL

CKD Staging Table (KDIGO 2024)

KDIGO (Kidney Disease: Improving Global Outcomes) defines six eGFR-based stages for chronic kidney disease. Note that CKD staging also incorporates albuminuria categories (A1–A3) for a complete G+A classification; eGFR alone provides only the G-category.

Stage	eGFR (mL/min/1.73m²)	Clinical Significance
G1	≥90	Normal or high. Kidney damage may still be present if other markers (e.g. albuminuria) exist.
G2	60–89	Mildly decreased. May be normal for age in older adults. Kidney damage markers determine CKD diagnosis.
G3a	45–59	Mild-to-moderate decrease. Increased risk of CKD progression and cardiovascular complications.
G3b	30–44	Moderate-to-severe decrease. Referral to nephrology is typically recommended.
G4	15–29	Severely decreased. Preparation for kidney replacement therapy (dialysis or transplant) should begin.
G5	<15	Kidney failure. Dialysis or kidney transplant is generally required to sustain life.

Why the Race Coefficient Was Removed (2021)

For over a decade, the standard 2009 CKD-EPI equation included a race-based multiplier: results for patients identified as Black were multiplied by 1.159, producing a systematically higher eGFR estimate. This adjustment was derived from observed average differences in serum creatinine between Black and non-Black participants in the development cohort — differences attributed, in part, to higher average muscle mass.

In September 2021, a joint task force convened by the National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) recommended removing the race coefficient. Their conclusion: race is a social and administrative construct, not a biological variable, and the race-based multiplier lacked a consistent physiological basis. Furthermore, the adjustment had measurable downstream consequences — Black patients with true kidney impairment could have their eGFR artificially inflated, delaying access to nephrology referral, transplant waitlisting, and other interventions. The 2021 equation eliminates this disparity, applying identical coefficients to all patients regardless of race or ethnicity.

Limits of eGFR

eGFR is an estimate, not a direct measurement of GFR. Its accuracy depends on several assumptions and is affected by factors unrelated to kidney filtration capacity:

Muscle mass. Creatinine is a byproduct of creatine metabolism in muscle. Individuals with very high muscle mass (e.g. bodybuilders) will have higher baseline creatinine and a lower calculated eGFR even if their kidneys are healthy. Conversely, people with low muscle mass (elderly, malnourished) may have deceptively low creatinine and a falsely reassuring eGFR.
Creatine supplementation. Oral creatine supplements are converted to creatinine and can transiently raise serum creatinine by 20–30%, lowering the eGFR estimate.
Recent cooked meat intake. Cooking converts creatine in meat to creatinine, which is absorbed after ingestion. A large meat meal in the 8–12 hours before a blood draw can meaningfully raise serum creatinine.
Pregnancy. GFR rises substantially during pregnancy (often by 40–50%), so the standard creatinine-based equations underestimate true GFR in pregnant individuals.
Stability assumption. The CKD-EPI equation assumes creatinine is at steady state. In acute kidney injury, creatinine is rising rapidly — eGFR calculated in this setting dramatically overestimates true filtration rate.
Certain medications. Trimethoprim, cimetidine, and some other drugs block tubular secretion of creatinine, raising serum creatinine without affecting GFR.

When creatinine-based eGFR may be unreliable, cystatin C-based or combined creatinine-cystatin C equations (also available in the 2021 CKD-EPI publication) provide a more accurate alternative.

When to Get Tested

eGFR is routinely reported whenever a serum creatinine is measured — most commonly as part of a basic or comprehensive metabolic panel (BMP/CMP). For healthy adults with no kidney risk factors, this is typically checked annually. More frequent monitoring is recommended for anyone with type 2 diabetes, hypertension, cardiovascular disease, obesity, a family history of kidney disease, or for those taking medications that affect kidney function (e.g. NSAIDs, ACE inhibitors, SGLT2 inhibitors). People already diagnosed with CKD should follow their nephrologist's monitoring schedule — often every 3–6 months for G3b–G4.

Track Your Kidney Biomarkers with Health3

eGFR is most meaningful when tracked over time. The Health3 app lets you log every blood test result, visualize trends, and share a clean summary with your doctor. It is especially useful for conditions closely linked to kidney function:

Frequently Asked Questions

What is eGFR and what does it measure?

eGFR stands for estimated glomerular filtration rate. It estimates how well your kidneys filter waste from your blood each minute, reported per 1.73 m² of body surface area. It is calculated from serum creatinine, age, and sex using the 2021 CKD-EPI equation and is the primary lab marker for assessing kidney function and staging chronic kidney disease (CKD).

Why was the race coefficient removed from the eGFR formula in 2021?

Older CKD-EPI equations (2009) multiplied eGFR by 1.159 for patients identified as Black, based on average differences in muscle mass observed in study populations. In September 2021, a joint NKF-ASN task force concluded that race is a social — not biological — variable, that the adjustment lacked a consistent physiological basis, and that it introduced systematic inequities in care (e.g. delaying transplant waitlisting for Black patients). The 2021 CKD-EPI equation removes the race coefficient entirely.

What does my CKD stage mean?

KDIGO classifies kidney function into stages G1 (≥90 mL/min/1.73m², normal), G2 (60–89, mildly decreased), G3a (45–59, mild-to-moderate), G3b (30–44, moderate-to-severe), G4 (15–29, severely decreased), and G5 (<15, kidney failure). A CKD diagnosis requires either an eGFR below 60 sustained for ≥3 months, or evidence of kidney damage (e.g. albuminuria, abnormal imaging). A single low reading does not confirm CKD.

How often should I test my eGFR?

Healthy adults with no kidney risk factors: annually as part of routine blood work. Those with diabetes, hypertension, cardiovascular disease, or CKD risk factors: at least annually, often more frequently. People with established CKD G3b–G4: typically every 3–6 months. Follow your doctor's guidance on frequency based on your individual situation.

What factors can falsely alter my creatinine and eGFR?

High muscle mass or creatine supplementation raises creatinine and lowers calculated eGFR. Low muscle mass (elderly, malnourished) lowers creatinine, producing a falsely reassuring eGFR. Eating a large meal of cooked meat in the 8–12 hours before the blood draw can raise creatinine. Pregnancy physiologically raises true GFR but the standard equation does not fully account for this. Certain medications (trimethoprim, cimetidine) block tubular secretion of creatinine without affecting kidney filtration.

Medical Disclaimer: This eGFR calculator is for educational and informational purposes only. It uses the 2021 CKD-EPI creatinine equation and produces an estimate, not a clinical measurement. A single eGFR value does not diagnose chronic kidney disease. CKD diagnosis requires either an eGFR <60 mL/min/1.73m² sustained for ≥3 months or the presence of kidney damage markers (albuminuria, abnormal imaging, or biopsy), confirmed by a qualified healthcare provider. eGFR may be less reliable in individuals with very high or very low muscle mass, creatine supplement use, pregnancy, acute kidney injury, or when creatinine is not at steady state. Do not use this tool to make medical decisions without consulting a physician or nephrologist.

Track Your eGFR Over Time

Trends matter more than single readings. Log your blood test results, monitor creatinine and eGFR across labs, and share a clear summary with your doctor — all in the Health3 app.