Nephrology · Clinical Tool

eGFR Calculator — CKD-EPI 2021

Calculate estimated glomerular filtration rate (eGFR) using the race-free CKD-EPI 2021 equation. Automatic CKD staging per KDIGO 2024 guidelines with drug dosing context.

CKD-EPI 2021 · race-free KDIGO 2024 staging Validated for adults

Input

Patient Parameters

Serum Creatinine (mg/dL)

Age (years)

Sex

Result

eGFR & CKD Stage

eGFR (CKD-EPI 2021)

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Enter values and press Calculate.

Reference

CKD Stages (KDIGO 2024)

Stage	eGFR (mL/min/1.73m²)	Description	Action
G1	≥ 90	Normal or high	Monitor + manage risk factors
G2	60–89	Mildly decreased	Monitor annually
G3a	45–59	Mildly–moderately decreased	Nephrology referral if progression
G3b	30–44	Moderately–severely decreased	Nephrology referral
G4	15–29	Severely decreased	Prepare for RRT
G5	< 15	Kidney failure	RRT or conservative management

Methodology: CKD-EPI 2021 Equation

The CKD-EPI 2021 equation was developed by Inker et al. and published in the New England Journal of Medicine (2021). It replaced the race-based 2009 version following recommendations from the NKF-ASN Task Force to remove race as a variable due to concerns about health equity.

eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^–1.200 × 0.9938^Age × Sex coefficient

Female: κ = 0.7, α = –0.241, sex coef = 1.012
Male: κ = 0.9, α = –0.302, sex coef = 1.000

Units: Scr in mg/dL · Age in years · eGFR in mL/min/1.73 m²

This calculator implements the full CKD-EPI 2021 equation as published, without race adjustment. Results are expressed as mL/min/1.73 m² (normalized to standard body surface area).

Clinical Use & Drug Dosing

eGFR is the cornerstone of CKD management. Key clinical applications include:

Drug dose adjustment (metformin, DOACs, aminoglycosides, NSAIDs, contrast media)
Staging and monitoring CKD progression with albuminuria (CGA classification)
Cardiovascular risk stratification — eGFR <60 independently increases CVD risk
Pre-procedural assessment (CT contrast, surgery, cardiac catheterization)
Transplant eligibility assessment

Note: Some drug labels (e.g., DOACs like dabigatran, rivaroxaban) use Cockcroft–Gault CrCl rather than eGFR for dosing. Always check the drug's SmPC.

Limitations

Not validated for children under 18 — use Bedside Schwartz equation instead
Not appropriate for acute kidney injury (AKI) — creatinine is not at steady state
Less accurate at extremes of muscle mass (sarcopenia, amputations, bodybuilders)
Single creatinine measurement — eGFR should be confirmed over ≥3 months for CKD diagnosis
Cystatin C–based eGFR may be more accurate when muscle mass is atypical
Creatine supplementation, meat consumption, and certain medications can raise creatinine artificially

Frequently Asked Questions

What is a normal eGFR level?

An eGFR ≥ 60 mL/min/1.73m² is generally considered normal in the absence of other markers of kidney damage. eGFR naturally declines with age — a value of 55 in a healthy 75-year-old may be expected and not represent CKD if there is no albuminuria.

What medications require dose adjustment for low eGFR?

Key medications requiring dose reduction or avoidance include: metformin (hold if eGFR <30), DOACs (dabigatran, rivaroxaban, apixaban, edoxaban — each has specific thresholds), allopurinol, digoxin, vancomycin, aminoglycosides, NSAIDs (avoid if eGFR <30), and iodinated contrast agents. Always consult drug-specific guidelines.

Why did the CKD-EPI equation remove race in 2021?

The 2009 equation included a race coefficient that assigned higher eGFR to Black patients. Critics argued this perpetuated systemic bias by potentially delaying nephrology referral. In 2021, the NKF-ASN task force recommended a race-free equation that performs comparably across populations.

How often should eGFR be monitored in CKD patients?

KDIGO 2024 recommends: G1–G2 low risk: annually; G3a–G3b: every 6 months; G4: every 3 months; G5: every 1–3 months. Rapid progression (>5 mL/min/year) warrants nephrology referral.

References

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
KDIGO 2024 CKD Guideline. Kidney Int. 2024;105(4S):S117–S314. kdigo.org
NKF-ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease. J Am Soc Nephrol. 2021;32(6):1305–1312.

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Medical Disclaimer: This calculator is for informational and educational purposes only. It does not constitute medical advice. Clinical decisions must always be made by a qualified healthcare professional. Drug dosing must be verified against current prescribing information.