eGFR Calculator

eGFR Calculator (CKD-EPI 2021)

Age (years)

Biological Sex

Serum Creatinine (mg/dL)

If your lab reports in μmol/L, divide by 88.4 to convert to mg/dL.

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eGFR (mL/min/1.73 m²)

Formula — CKD-EPI 2021

eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^Age × [1.012 if Female]
κ = 0.7 (Female) or 0.9 (Male) · α = −0.241 (Female) or −0.302 (Male)

CKD Staging (KDIGO 2012)

Stage	eGFR (mL/min/1.73 m²)	Description	Monitoring
G1	≥ 90	Normal or high (requires other markers of kidney damage for CKD diagnosis)	Annually if at risk
G2	60–89	Mildly decreased	Annually
G3a	45–59	Mildly to moderately decreased	Every 6 months
G3b	30–44	Moderately to severely decreased	Every 3 months
G4	15–29	Severely decreased — nephrology referral	Every 3 months; prepare for RRT
G5	< 15	Kidney failure — dialysis / transplantation	Continuous nephrology care

Clinical Application

Drug dosing: eGFR is used to adjust doses of renally cleared drugs — NSAIDs, metformin (stop if <30), SGLT2 inhibitors (reduced efficacy if <45), direct oral anticoagulants, aminoglycosides, carboplatin (Calvert formula uses measured GFR ideally). Note that some drug labelling uses creatinine clearance (CrCl, Cockcroft-Gault) — these are not interchangeable; check drug summary for the method required.
Contrast media: KDIGO 2023 recommends that iodinated contrast is safe in eGFR ≥ 30; exercise caution at eGFR 20–29; ensure hydration. Gadolinium-based contrast agents (MRI): nephrogenic systemic fibrosis risk is low with modern macrocyclic agents even at low eGFR — but use with caution in G4–G5.
CKD diagnosis requires albuminuria assessment: CKD is defined as abnormality of kidney structure or function for ≥ 3 months. G1 and G2 require at least one marker of kidney damage (albuminuria, abnormal urinalysis, structural abnormality) to diagnose CKD — eGFR alone is insufficient.
CKD-EPI 2021 vs. prior equations: The 2021 race-free version was adopted following evidence that using Black race as a correction factor was clinically inequitable. The 2021 equation has similar or slightly better performance to the 2009 equation in diverse populations.
Creatinine-based eGFR can be misleading in conditions affecting muscle mass (malnutrition, sarcopenia, amputations, bodybuilding). In these cases, cystatin C-based eGFR (or CKD-EPI creatinine-cystatin combination) is more reliable.

References

Inker LA, et al. New Creatinine- and Cystatin C–Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385(19):1737–1749.
KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int Suppl. 2013;3(1):1–150.

Formula — CKD-EPI 2021

CKD Staging (KDIGO 2012)

Clinical Application

References

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