GFR calculator
Free GFR Calculator — Estimate Kidney Function for Adults & Children (CKD-EPI, MDRD, Cockcroft–Gault, Schwartz)
The GFR Calculator (Glomerular Filtration Rate Calculator) helps you accurately estimate kidney function using clinically verified equations — CKD-EPI 2021, CKD-EPI 2009, MDRD, Cockcroft–Gault, and Bedside Schwartz for children. It automatically detects adult or pediatric inputs and displays estimated eGFR (mL/min/1.73 m²) values based on your age, sex, weight, height, and serum creatinine level. These equations are used globally by nephrologists to assess kidney health and detect chronic kidney disease (CKD).
How to Use the GFR Calculator
- Enter your age, sex, and serum creatinine (in mg/dL or µmol/L).
- Optionally enter weight (for Cockcroft–Gault) and height (for pediatric formulas).
- Select the desired formula or use “Auto” mode — it automatically chooses CKD-EPI for adults and Schwartz for children.
- Click Calculate to see your eGFR value, plus detailed notes about the result.
- Compare the outcome across multiple scientific equations and identify your CKD stage.
Formulas Used in GFR Calculation
The calculator supports several validated formulas used in modern nephrology:
- CKD-EPI 2021 (race-free):
eGFR = 142 × min(SCr/k, 1)a × max(SCr/k, 1)−1.200 × (0.9938)Age × [1.012 if female]
— Developed to remove race correction and improve accuracy across populations.
Source: Levey et al., NEJM, 2021 - CKD-EPI 2009:
eGFR = 141 × min(SCr/k, 1)a × max(SCr/k, 1)−1.209 × 0.993Age × [1.018 if female] × [1.159 if Black]
Source: Levey et al., Ann Intern Med, 2009 - MDRD (Modification of Diet in Renal Disease):
eGFR = 175 × (SCr)−1.154 × (Age)−0.203 × [0.742 if female] × [1.212 if Black]
Source: Levey et al., Ann Intern Med, 1999 - Cockcroft–Gault (1976):
CrCl = ((140 − Age) × Weight × [0.85 if female]) / (72 × SCr)
Normalized for body surface area (BSA): CrClnorm = CrCl × (1.73 / BSA)
Source: Cockcroft & Gault, Nephron, 1976 - Bedside Schwartz (2009, pediatric):
eGFR = (0.413 × Height in cm) / SCr
Source: Schwartz et al., J Am Soc Nephrol, 2009
CKD Stages by eGFR
- Stage 1: eGFR ≥ 90 — Normal kidney function
- Stage 2: 60–89 — Mildly decreased
- Stage 3: 30–59 — Moderately decreased
- Stage 4: 15–29 — Severely decreased
- Stage 5: <15 — Kidney failure (end-stage CKD)
Why This GFR Calculator Is Reliable
- Uses all major clinical formulas for comparison (CKD-EPI, MDRD, Cockcroft–Gault, Schwartz).
- Includes both adult and pediatric equations in one tool.
- Applies verified reference values from NKF, KDIGO, and NEJM studies.
- Supports BSA normalization for Cockcroft–Gault results.
- Instant, responsive, and accurate — ideal for clinicians and medical students.
References
FAQ — GFR Calculator
1. What is GFR?
GFR (Glomerular Filtration Rate) measures how well your kidneys filter blood, reported in mL/min/1.73 m².
2. What is eGFR?
eGFR is the “estimated” GFR value derived from creatinine levels, age, sex, and other parameters.
3. Which formula is most accurate?
The CKD-EPI 2021 race-free formula is currently the most accurate for adult patients, endorsed by the KDIGO guidelines.
4. How is Cockcroft–Gault normalized to BSA?
The Cockcroft–Gault equation estimates creatinine clearance (CrCl). To compare it with eGFR, it’s normalized to 1.73 m² body surface area using the Du Bois formula: BSA = 0.007184 × Height⁰·⁷²⁵ × Weight⁰·⁴²⁵.
5. Can this calculator be used for children?
Yes, if age is under 18, the Bedside Schwartz (2009) formula is automatically applied.
6. What units should I use?
You can input serum creatinine in either mg/dL or µmol/L — the calculator converts automatically.
