What is the 2021 CKD-EPI equation?

The 2021 CKD-EPI creatinine equation estimates eGFR using serum creatinine, age, and biological sex — without a race variable. 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 from the equation?

The original 2009 CKD-EPI equation included a multiplier for Black race that systematically produced higher eGFR estimates for Black patients, potentially delaying CKD diagnosis. The 2021 revision removes this coefficient, applying a single equation equally to all patients regardless of race or ethnicity.

What is a normal GFR?

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

How does eGFR differ from creatinine clearance (CrCl)?

eGFR from CKD-EPI is normalized to body surface area (1.73 m²), making it comparable across patients of different sizes and is used for CKD staging. Creatinine clearance from Cockcroft-Gault is not BSA-adjusted and is preferred for calculating renal drug dose adjustments.

Can I use this calculator for pediatric patients?

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

What creatinine units does this calculator support?

The calculator accepts serum creatinine in both mg/dL and µmol/L. Switching the unit toggle automatically converts any value already entered so you never need to convert manually.

GFR CKD-EPI Calculator

Calculate your estimated GFR using the 2021 CKD-EPI creatinine equation and instantly determine your CKD stage.

Patient Parameters

Age (years)

Biological Sex

Serum Creatinine

Normal: 0.74–1.35 mg/dL (male), 0.59–1.04 mg/dL (female)

2021 CKD-EPI Formula

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)

Enter patient parameters and click Calculate GFR to see results.

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 and screening purposes only. CKD diagnosis requires at least two eGFR readings separated by at least 90 days. Staging should also incorporate albuminuria (urine ACR) and underlying clinical context. Results do not replace laboratory-reported values or professional clinical judgment.

Summary

The GFR CKD-EPI Calculator uses the 2021 CKD-EPI creatinine equation — the current clinical standard endorsed by the National Kidney Foundation and American Society of Nephrology — to estimate glomerular filtration rate (eGFR) from serum creatinine, age, and biological sex. The 2021 revision removes the race variable used in the older 2009 equation, producing a single race-free formula that applies to all patients. Results are expressed in mL/min/1.73 m² and mapped to KDIGO CKD stages G1 through G5 with clinical context.

How it works

Enter the patient age in years (18 or older — the equation is not validated for children).
Select biological sex to apply the correct kappa and alpha coefficients.
Enter serum creatinine in mg/dL, or switch to µmol/L for automatic unit conversion.
Click Calculate GFR to run the 2021 CKD-EPI formula.
Review the eGFR result, KDIGO CKD stage, color-coded severity bar, and full equation breakdown.
Use the staging reference table to understand clinical implications for the calculated eGFR.

Use cases

Stage chronic kidney disease using the current guideline-recommended equation.
Monitor kidney function trends in patients with diabetes or hypertension.
Screen patients before starting drugs with eGFR-based dosing thresholds.
Assess renal function prior to contrast agent administration.
Support nephrology referral decisions when eGFR drops below 30 mL/min/1.73 m².
Educate patients on what their creatinine lab result means for kidney function.
Determine eligibility for SGLT2 inhibitors and other renal-threshold medications.
Research and academic use for understanding the 2021 CKD-EPI equation derivation.

Frequently Asked Questions

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