GFR Calculator

Calculate GFR and creatinine clearance using the Cockcroft-Gault equation. Get CKD staging (G1-G5), BSA-adjusted GFR, and ideal body weight corrections for obese patients.

yrs
kg
mg/dL
Creatinine Clearance (mL/min)
—
CKD Stage —
Kidney Function —
Extended More scenarios, charts & detailed breakdown ▾
yrs
kg
mg/dL
CrCl (mL/min)
—
CKD Stage —
Professional Full parameters & maximum detail ▾
yrs
kg
cm
mg/dL
CrCl (IBW)
—
Ideal Body Weight (kg) —
Adjusted Body Weight (kg) —
CrCl (Actual BW) —
CrCl (Adjusted BW, if obese) —
CKD Stage —

How to Use This Calculator

  1. Enter your age, weight in kg, and serum creatinine in mg/dL.
  2. Select your sex.
  3. Results show CrCl in mL/min and CKD stage (G1-G5).
  4. Use BSA Adjusted for the normalised GFR per 1.73 m2 body surface area.

Formula

CrCl = ((140 - age) x weight x sex factor) / (72 x serum Cr)

Sex factor: 1.0 for males, 0.85 for females. BSA-adjusted: CrCl x 1.73 / BSA (DuBois formula).

Example

Example: 55-year-old male, 75 kg, Cr = 1.2 mg/dL. CrCl = (140 - 55) x 75 x 1.0 / (72 x 1.2) = 6375 / 86.4 = 73.8 mL/min (CKD Stage G2).

Frequently Asked Questions

  • Glomerular Filtration Rate (GFR) measures how well the kidneys filter blood. It is the primary marker for CKD staging. GFR >= 90 mL/min is normal; GFR < 15 mL/min indicates kidney failure requiring dialysis or transplant.
  • CrCl = ((140 - age) x weight x 0.85 if female) / (72 x serum creatinine). Developed in 1976 from 249 patients. Still widely used for drug dosing because FDA guidelines often reference it specifically.
  • The eGFR (CKD-EPI or MDRD) is the standard for CKD staging and uses age, sex, and creatinine without requiring weight. Cockcroft-Gault is still preferred for drug dosing. For CKD classification and monitoring, see the eGFR calculator.
  • For non-obese patients, use actual body weight. For obese patients (BMI > 30 or weight > 130% of IBW), use ideal body weight (IBW) or adjusted body weight (ABW = IBW + 0.4 x (ABW - IBW)). The professional tab calculates both.
  • KDIGO 2024: G1 (>=90 mL/min) = normal, G2 (60-89) = mildly decreased, G3a (45-59) = mildly-moderately decreased, G3b (30-44) = moderately-severely decreased, G4 (15-29) = severely decreased, G5 (<15) = kidney failure.

Related Calculators

🫘 eGFR Calculator (CKD-EPI) 💧 Creatinine Clearance ⚖️ BMI Calculator 📐 Body Surface Area
Sources & References (5) ▾
  1. KDIGO 2024 CKD Guidelines — Evaluation and Management — KDIGO / National Kidney Foundation
  2. Cockcroft DW & Gault MH (1976) — Prediction of Creatinine Clearance from Serum Creatinine, Nephron — Nephron / Karger
  3. NIDDK — Estimating Kidney Function — NIH / NIDDK
  4. National Kidney Foundation — GFR and CKD Staging — National Kidney Foundation
  5. NCBI StatPearls — Creatinine Clearance (Cockcroft-Gault Equation) — NCBI / StatPearls