eGFR

GFR Kidney Function Calculator

Cockcroft-Gault estimated GFR with a kidney-function stage.

Age (years)

Weight (kg)

Serum creatinine (mg/dL)

Estimated GFR

99 mL/min

Stage: Normal

Cockcroft-Gault estimate. Clinical decisions require physician interpretation and full labs.

What you entered

Age: 45Weight: 75 kgCreatinine: 1 mg/dLGender: male

1
Cockcroft-Gault base formula
((140−45) × 75) ÷ (72 × 1)= 99.0 mL/min
2
Compare to CKD stage thresholds
Normal ≥90 · Mild 60–89 · Moderate 30–59 · Severe 15–29 · Failure <15= Normal

Result

Estimated GFR: 99 mL/min

Estimated kidney filtration rate is 99 mL/min — classified as "Normal". This is a screening estimate only, not a diagnosis.

Cockcroft-Gault eGFR by serum creatinine for two reference patients

Serum creatinine is the lab value that moves eGFR most, so these rows hold age and weight fixed and vary creatinine only. The first pair of columns is a 55-year-old man at 70 kg, the second a 55-year-old woman at 60 kg.

Serum creatinine (mg/dL)	Man 55 yrs, 70 kg: eGFR (mL/min)	Man: stage	Woman 55 yrs, 60 kg: eGFR (mL/min)	Woman: stage
0.7	118.1	Normal	86.0	Mildly decreased
0.9	91.8	Normal	66.9	Mildly decreased
1.0	82.6	Mildly decreased	60.2	Mildly decreased
1.2	68.9	Mildly decreased	50.2	Moderately decreased
1.5	55.1	Moderately decreased	40.1	Moderately decreased
1.8	45.9	Moderately decreased	33.4	Moderately decreased
2.2	37.6	Moderately decreased	27.4	Severely decreased
3.0	27.5	Severely decreased	20.1	Severely decreased
4.0	20.7	Severely decreased	15.1	Severely decreased

Cockcroft-Gault multiplies the female result by 0.85 and scales directly with body weight, so the woman's column is lower for both reasons. eGFR also falls with age at fixed creatinine, since the formula uses a 140 minus age term. These figures are illustrative and are not a diagnosis: most labs now report CKD-EPI rather than Cockcroft-Gault and the two disagree, a single creatinine reading moves with hydration, muscle mass, and recent protein intake, and any low result needs a repeat test and a doctor's interpretation.

What GFR measures

Glomerular filtration rate estimates how much blood your kidneys filter per minute — the standard way clinicians gauge kidney function, since filtration capacity declines predictably as kidney disease progresses.

Why age, weight, and sex all factor in

The Cockcroft-Gault equation uses serum creatinine along with age, weight, and sex because muscle mass (which produces creatinine) varies systematically across these factors, and the formula corrects for that to avoid skewed estimates.

Frequently asked questions

What is a normal GFR?

A GFR of 90+ mL/min is normal. Stage 1 CKD: GFR ≥90 with other kidney damage signs. Stage 2: 60–89. Stage 3a: 45–59. Stage 3b: 30–44. Stage 4: 15–29. Stage 5 (kidney failure): <15. GFR naturally declines with age — losing ~1 mL/min/year after 30 is normal. A single low reading should be confirmed with repeat testing.

What does a low GFR mean?

A GFR below 60 sustained for 3+ months indicates chronic kidney disease. Causes include diabetes (most common), high blood pressure, glomerulonephritis, and polycystic kidney disease. A low GFR doesn't always cause symptoms — many people discover it through routine blood work. Early detection allows treatment to slow progression.

How can I improve my GFR?

You can slow GFR decline with: blood pressure control (<130/80), blood sugar management, reducing sodium intake, staying hydrated, avoiding NSAIDs (ibuprofen, naproxen), limiting protein if kidney disease is advanced, and quitting smoking. Exercise and weight loss also help. Once significant kidney function is lost, it typically can't be fully restored.