Creatinine Clearance / GFR Calculator
Estimate adult eGFR, creatinine clearance (CrCl), or pediatric GFR — with CKD stage interpretation, optional albuminuria (ACR) classification, a kidney-risk matrix, and an optional method-comparison drawer, each with clear step-by-step math.
Background
Kidney function is often estimated from serum creatinine together with age, sex, and sometimes body size. Adult eGFR is commonly reported in mL/min/1.73 m². Dosing-style creatinine clearance is typically reported in mL/min. In children, a height-based pediatric equation is used instead.
How to use this calculator
- Choose Adult eGFR, Creatinine Clearance, or Pediatric GFR.
- Enter the required measurements, making sure the serum creatinine unit is correct.
- In Adult mode, optionally add ACR for an albuminuria category and kidney-risk matrix, or turn on the method comparison.
- Click Calculate to see the headline estimate, its category, and (if enabled) the interpretation and step-by-step math.
How This Calculator Works
Adult eGFR uses the 2021 CKD-EPI creatinine equation (race-free) and reports mL/min/1.73 m², mapped to standard G1–G5 categories.
Creatinine Clearance uses the Cockcroft-Gault equation and reports mL/min — a dosing-style estimate, not the same thing as standardized eGFR.
Pediatric GFR uses the bedside Schwartz equation, which needs only height and serum creatinine.
If you add urine ACR, the calculator assigns an albuminuria category (A1/A2/A3) and combines it with the GFR category on the standard KDIGO risk matrix to show an overall kidney-risk level.
The method comparison shows CKD-EPI 2021 alongside Cockcroft-Gault and MDRD so you can see how different equations can disagree — they use different inputs and assumptions, so exact matches aren't expected.
Formulas & Equations Used
Adult eGFR (CKD-EPI 2021): eGFR = 142 · min(SCr/κ,1)α · max(SCr/κ,1)−1.200 · 0.9938Age · 1.012 (if female)
Creatinine clearance (Cockcroft-Gault): CrCl = ((140 − Age) · Weight) / (72 · SCr), × 0.85 if female
Pediatric GFR (bedside Schwartz): eGFR = 0.413 · Height(cm) / SCr
Optional BSA (Mosteller): BSA = √((Height(cm) · Weight(kg))/3600)
Example Problems & Step-by-Step Solutions
Example 1 — Adult eGFR
A 45-year-old male has SCr = 1.0 mg/dL.
Step: κ=0.9, α=−0.302. SCr/κ=1.111.
Result: eGFR ≈ 94.6 mL/min/1.73 m² (G1).
Example 2 — Creatinine clearance
A 67-year-old female, 62 kg, has SCr = 1.3 mg/dL.
Step: ((140−67)·62)/(72·1.3), ×0.85.
Result: CrCl ≈ 41.1 mL/min.
Example 3 — Pediatric GFR
A child has height = 128 cm, SCr = 0.7 mg/dL.
Step: 0.413 × 128 / 0.7.
Result: eGFR ≈ 75.5 mL/min/1.73 m².
Example 4 — Combined GFR + albuminuria risk
Adult eGFR lands in G3a (45–59) and ACR is 85 mg/g (A2).
Step: Look up G3a × A2 on the KDIGO risk matrix.
Result: Combined risk is high — higher than either category would suggest alone.
Frequently Asked Questions
Is eGFR the same as creatinine clearance?
No. Adult eGFR is standardized to 1.73 m² for comparing across people, while Cockcroft-Gault creatinine clearance is a dosing-style estimate reported in mL/min for one specific person's body size.
What do A1, A2, and A3 mean?
Albuminuria categories based on urine ACR: A1 < 30 mg/g, A2 30–300 mg/g, A3 > 300 mg/g.
Why does the risk matrix show a higher risk than the GFR category alone?
Albuminuria is an independent risk marker. KDIGO's matrix combines GFR category and albuminuria category because the two together predict outcomes better than either alone — that's why G3a with A2 albuminuria is riskier than G3a with A1.
Why can CKD-EPI, Cockcroft-Gault, and MDRD disagree?
They're different equations with different assumptions and inputs (Cockcroft-Gault needs weight; the others don't). All three are used in different clinical contexts, so their estimates won't always match exactly.
Why is Creatinine Clearance mode limited to ages 18–139?
Cockcroft-Gault's (140 − Age) term goes to zero at age 140 and negative beyond it, producing a nonsensical negative clearance. It's also an adult-only formula, so ages under 18 aren't accepted either.
Does a low eGFR automatically mean CKD?
Not by itself. This calculator estimates kidney function; diagnosis depends on the broader clinical picture and other kidney-damage markers.
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