What is the 2021 CKD-EPI equation?

The 2021 CKD-EPI creatinine equation estimates eGFR using age, sex, and serum creatinine, without a race coefficient. It was developed by the CKD-EPI consortium and endorsed by the NKF-ASN Task Force to eliminate race-based disparities in kidney function estimation. The formula uses sex-specific kappa and alpha constants and a two-piece power function of SCr/kappa.

Why was the race variable removed?

The original 2009 CKD-EPI equation included a multiplier for Black race, which systematically produced higher eGFR estimates for Black patients and could delay diagnosis of kidney disease. The 2021 revision removes this coefficient, producing a single equation that applies equally to all patients regardless of race or ethnicity.

What is a normal eGFR?

An eGFR of 60 mL/min/1.73 m² or above is generally considered within the normal to mildly impaired range. Values of 90 and above (G1) are normal or high. eGFR naturally declines with age, so older adults often have values in the 60–89 range (G2) without underlying disease.

How does eGFR differ from creatinine clearance (CrCl)?

eGFR from CKD-EPI is adjusted for body surface area (BSA) and standardized to 1.73 m², making it comparable across patients of different sizes. CrCl from Cockcroft-Gault is not BSA-adjusted and is preferred for drug dosing. eGFR is used for CKD staging; CrCl is used for renal drug dose adjustment.

Can I use this for patients under 18?

No. The CKD-EPI equation is validated for adults aged 18 and older. Pediatric eGFR is estimated with the Bedside Schwartz equation or CKiD formula. Do not use this tool for children or adolescents.

When should I refer a patient to a nephrologist?

KDIGO guidelines generally recommend nephrology referral for patients with eGFR below 30 mL/min/1.73 m² (Stage G4–G5), rapid decline (>5 mL/min/1.73 m² per year), significant proteinuria, or uncertainty about the cause of CKD. This calculator provides a screening estimate — clinical judgment is always required.

CKD-EPI 2021 eGFR Calculator

Calculate eGFR using the 2021 race-free CKD-EPI creatinine equation and determine your CKD stage instantly.

Patient Parameters

Age (years)

Biological Sex

Serum Creatinine

Normal: 0.74–1.35 mg/dL (men), 0.59–1.04 mg/dL (women)

2021 CKD-EPI Equation

eGFR = 142 × min(SCr/κ, 1)^α × max(SCr/κ, 1)^−1.200 × 0.9938^Age
Female: × 1.012 | κ: 0.7 (F), 0.9 (M) | α: −0.241 (F), −0.302 (M)

Fill in the parameters on the left and click Calculate eGFR

Estimated GFR (eGFR)

— mL/min/1.73 m²

CKD Stage

—

0 15 30 60 90 120+

—

Equation Breakdown

KDIGO CKD Staging Reference

Stage	eGFR (mL/min/1.73 m²)	Description

Clinical note: This tool is for educational reference only. eGFR is a screening estimate — diagnosis of CKD requires at least two readings separated by 90 days. CKD staging should also incorporate albuminuria and clinical context. Results do not replace professional clinical judgment or laboratory-reported values.

Summary

The 2021 CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation estimates eGFR from serum creatinine, age, and sex without a race variable, following the National Kidney Foundation and American Society of Nephrology recommendation to remove race coefficients. It is the current standard for CKD staging and is used to identify kidney disease, monitor its progression, and guide treatment decisions. Results are expressed in mL/min/1.73 m² and map directly to KDIGO CKD stages G1 through G5.

How it works

Enter the patient's age in years (must be 18 or older).
Select biological sex — the equation uses different κ (kappa) and α (alpha) coefficients for males and females.
Enter serum creatinine in mg/dL or switch to µmol/L for automatic unit conversion.
Click Calculate eGFR to apply the 2021 CKD-EPI formula.
Review the eGFR value, KDIGO CKD stage, and the full equation breakdown.
Use the staging table to understand kidney function categories and clinical implications.

Use cases

Stage chronic kidney disease using the current guideline-recommended equation.
Monitor kidney function trends in patients with diabetes, hypertension, or glomerular disease.
Assess renal function before initiating nephrotoxic medications or contrast agents.
Determine eligibility for drugs with eGFR-based dosing thresholds (e.g., SGLT2 inhibitors, metformin).
Support nephrology referral decisions when eGFR falls below 30 mL/min/1.73 m².
Educate patients about kidney function numbers during clinical consultations.
Screen high-risk populations for early-stage CKD that may be asymptomatic.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu