Kidney Function

GFR Calculator

Estimate glomerular filtration rate (GFR) using MDRD, CKD-EPI, and Mayo Quadratic equations. Compare staging, population means, and download nephrology-ready summaries.

MDRD

82.8 mL/min/1.73m²

CKD-EPI

93.7 mL/min/1.73m²

Mayo Quadratic

88.8 mL/min/1.73m²

Average eGFR

88.4

CKD Stage

G2 · Mildly decreased

Monitor if albuminuria present.

What is GFR?

Glomerular filtration rate measures how much blood your kidneys filter per minute. Clinicians rely on eGFR equations— such as MDRD and CKD-EPI—because direct measurement requires radioisotope or iohexol clearance. eGFR helps stratify chronic kidney disease (CKD) risk and guides medication dosing, imaging contrast decisions, and timing of specialist referral.

eGFR estimates carry limitations: extremes of muscle mass, acute kidney injury, liver failure, pregnancy, and certain medications can distort serum creatinine. Cystatin-C–based equations or measured clearance may be needed in these scenarios.

Chronic Kidney Disease Stages

Stage	GFR (mL/min/1.73m²)	Description	Clinical notes
G1	≥ 90	Normal or high	No evidence of kidney damage.
G2	60-89	Mildly decreased	Monitor if albuminuria present.
G3a	45-59	Mild to moderate decrease	Early CKD; optimize risk factors.
G3b	30-44	Moderate to severe decrease	Refer to nephrology, monitor labs.
G4	15-29	Severely decreased	Prepare for renal replacement therapy.
G5	< 15	Kidney failure	Dialysis or transplant indicated.

Population mean eGFR

Age group	Mean GFR
20-29	116 mL/min/1.73m²
30-39	107 mL/min/1.73m²
40-49	99 mL/min/1.73m²
50-59	93 mL/min/1.73m²
60-69	85 mL/min/1.73m²
70+	75 mL/min/1.73m²

Pediatric Schwartz equation

Child height (cm)

Serum creatinine (mg/dL)

Estimated pediatric GFR

82.6 mL/min/1.73m²

Schwartz constant 0.413 × height (cm) ÷ serum creatinine (mg/dL).