Free creatinine clearance calculator using the Cockcroft-Gault formula. Enter age, weight, sex & serum creatinine for an instant mL/min estimate.
Medical disclaimer: This tool is for informational purposes only and is not medical advice. Creatinine clearance is an estimate of kidney function — it is less accurate with unstable kidney function, extreme body sizes, very low muscle mass, pregnancy, or acute illness. Consult a qualified clinician for interpretation and any medication dosing decisions. Never adjust medication based on this estimate.
Creatinine clearance is the standard bedside estimate of how well your kidneys filter waste from the blood. Our free creatinine clearance calculator uses the Cockcroft-Gault equation — the formula behind most medication dose adjustments for kidney function — taking your age, body weight, sex, and serum creatinine level and returning an estimate in mL/min along with a kidney-disease stage note (G1–G5).
Creatinine is a waste product from normal muscle metabolism that healthy kidneys filter out at a fairly steady rate. When kidney function drops, creatinine builds up in the blood, so higher serum creatinine means lower clearance — and lower clearance means the kidneys are filtering less.
Creatinine clearance (CrCl) estimates the volume of blood plasma the kidneys clear of creatinine per minute. A healthy young adult is typically around 90–120 mL/min. Because drug doses are cleared through the kidneys too, pharmacists and clinicians use the Cockcroft-Gault equation to decide whether medications need dose reductions in impaired kidney function.
Keep in mind this is an estimate. The formula assumes stable kidney function, average muscle mass, and normal body composition — it is less accurate during acute illness, with extreme body sizes, very low muscle mass, or pregnancy. Your doctor may confirm with a 24-hour urine collection or cystatin C testing.
CrCl (mL/min) = ((140 − age) × weight in kg × (0.85 if female)) ÷ (72 × serum creatinine in mg/dL)
Worked example: a 50-year-old woman weighing 75 kg with serum creatinine 1.1 mg/dL: ((140 − 50) × 75 × 0.85) ÷ (72 × 1.1) = (90 × 75 × 0.85) ÷ 79.2 = 5,737.5 ÷ 79.2 ≈ 72.4 mL/min — mildly decreased function (G2 range), a level at which some medications begin to need review.
Kidney function stages (by estimated clearance): G1 ≥90 (normal/high), G2 60–89 (mildly decreased), G3a 45–59 (mild-moderate), G3b 30–44 (moderate-severe), G4 15–29 (severely decreased), G5 <15 (kidney failure).
Consider a 72-year-old man weighing 70 kg with serum creatinine 1.4 mg/dL: ((140 − 72) × 70) ÷ (72 × 1.4) = 4,760 ÷ 100.8 ≈ 47 mL/min — G3a. Even though his creatinine looks only modestly elevated, his clearance is roughly half of normal because of his age. This is exactly why hospitals calculate it before prescribing antibiotics, blood thinners, or diabetes drugs: the number on the lab report alone doesn’t tell the whole story, and many medications are dose-reduced once clearance falls below 50 or 30 mL/min.
BMR Calculator — your basal metabolic rate, another key number derived from age, weight, and sex.
TDEE Calculator — total daily energy expenditure for nutrition planning alongside kidney-friendly diets.
Body Fat Calculator — body composition matters because creatinine depends on muscle mass.
Calorie Calculator — plan daily intake, useful when protein or sodium needs restricting.
One Rep Max Calculator — strength training builds the muscle that keeps creatinine generation stable.
This page is a free creatinine clearance calculator on Sigma Calculator (sigmacalculator.net) implementing the Cockcroft-Gault equation: ((140 − age) × weight_kg × 0.85 if female) ÷ (72 × serum creatinine mg/dL). Inputs are age, weight (kg/lbs toggle), sex, and serum creatinine; output is estimated clearance in mL/min plus a CKD stage note (G1 ≥90 through G5 <15). Medical disclaimer: estimate only, less accurate with unstable kidney function, extreme body size, low muscle mass, or pregnancy; consult a clinician; not for medication dosing decisions without professional review.
For a healthy young adult, creatinine clearance is typically 90–120 mL/min. Clearance naturally falls with age — a value of 60–89 mL/min in an older adult may be normal, which is why the stage note should be interpreted alongside a clinician’s review.
The Cockcroft-Gault equation applies a 0.85 factor for women because women typically have less muscle mass and therefore generate less creatinine — so the same serum creatinine level corresponds to lower clearance in women. It is a population average, not exact for every individual.
Both estimate kidney filtration. Cockcroft-Gault (used here) is the standard for medication dose adjustments and uses weight directly. eGFR (CKD-EPI) is standardized to body surface area and is the number usually reported by labs for CKD staging. For drug dosing, guidelines generally prefer Cockcroft-Gault.
The estimate is unreliable with rapidly changing kidney function (acute illness or hospitalization), very low or very high muscle mass, amputation, pregnancy, or severe malnutrition — in all of these, creatinine is not a steady marker. Ask your clinician about measured clearance (24-hour urine) or cystatin C instead.
Very high clearance (above ~130 mL/min) can occur in pregnancy or with high protein intake, and it matters clinically because it can mean drugs are cleared faster than expected. If your estimate looks unusually high, bring it to your clinician rather than assuming it is ideal.
Cite this page as: “Creatinine Clearance Calculator.” Sigma Calculator. Accessed October 20, 2026. https://sigmacalculator.net/fitness-health-calculators/creatinine-clearance-calculator/
Last updated: October 20, 2026