45-year-old male, creatinine 1.0 mg/dL
CKD-EPI 2021: 142 × (1.0/0.9)^(-0.302) × 0.9938^45 ≈ 92 mL/min/1.73m². Stage G1 - normal. Reassess annually; check urine albumin to rule out early kidney damage despite normal GFR.
GFR Calculator - Kostenloser Online-Rechner
GFR (Glomerular Filtration Rate) is the most important measure of kidney function. This calculator uses the CKD-EPI 2021 formula - the current race-free standard - and the older Cockcroft-Gault formula for comparison. Includes CKD stage classification.
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yr
mg/dL
From your blood report
kg
Used by Cockcroft-Gault only
eGFR (CKD-EPI 2021)
95 mL/min/1.73m²
G1 · Normal
CrCl (Cockcroft-Gault)
92 mL/min
Used for drug dosing
CKD stage G1 - Normal
Normal kidney function. No action required other than maintaining hydration and avoiding NSAID overuse.
CKD stages
G1 ≥90 · G2 60-89 · G3a 45-59 · G3b 30-44 · G4 15-29 · G5 <15 (dialysis territory)
Self-calculated eGFR is informational only - diagnosis and staging require sustained values over 3+ months and clinical context. Speak to a nephrologist for any GFR <60 or rapid decline.
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GFR Calculator verstehen
Glomerular Filtration Rate (GFR) is the single most important indicator of kidney function. It estimates how much blood your kidneys filter per minute, normalized to body surface area (mL/min/1.73m²). Tracking GFR is essential for detecting Chronic Kidney Disease (CKD) early - when intervention can slow progression and prevent dialysis or transplant later. India has one of the world's highest CKD burdens, driven largely by diabetes (45% of CKD cases) and hypertension (25%), with an estimated 17% of adults affected.
This calculator uses the CKD-EPI 2021 formula, the current global gold standard for GFR estimation. The 2021 revision removed the race coefficient that older formulas included - a significant medical advance recognising that race is not a biological variable. It also includes the older Cockcroft-Gault formula for comparison, since some pharmaceutical dosing protocols still reference it. Inputs are minimal: serum creatinine (from any routine blood test), age, sex, and optionally weight.
GFR Calculator in 4 Schritten nutzen
Enter your serum creatinine in mg/dL (from a recent blood test).
Enter your age and gender.
Enter weight (only used by Cockcroft-Gault).
Read your eGFR and CKD stage.
So funktioniert GFR Calculator
CKD-EPI 2021 uses creatinine, age and sex (no race factor since the 2021 revision). Output is in mL/min/1.73m². Cockcroft-Gault adds weight and is still used for some drug dosing despite being less accurate for CKD staging.
Formula
CKD-EPI 2021: 142 × min(cr/k,1)^a × max(cr/k,1)^−1.2 × 0.9938^age × (1.012 if female)
- crSerum creatinine in mg/dL
- k0.7 (female) or 0.9 (male)
- a−0.241 (female) or −0.302 (male)
Wie GFR Calculator zum Ergebnis kommt
CKD-EPI 2021 formula: 142 × min(cr/k, 1)^α × max(cr/k, 1)^(-1.2) × 0.9938^age × (1.012 if female). Where cr = serum creatinine in mg/dL, k = 0.7 for women / 0.9 for men, α = -0.241 for women / -0.302 for men. This produces an eGFR in mL/min/1.73m². The formula is calibrated to match measured GFR (from inulin or iothalamate clearance) across a wide population.
CKD staging by GFR: Stage G1 (≥90): Normal or high - kidney damage with normal function (requires albuminuria detection too). Stage G2 (60-89): Mildly decreased. Stage G3a (45-59): Mildly to moderately decreased. Stage G3b (30-44): Moderately to severely decreased. Stage G4 (15-29): Severely decreased. Stage G5 (<15): Kidney failure - dialysis or transplant typically required. Most patients in stages G1-G2 are asymptomatic; early detection requires routine creatinine testing.
GFR naturally declines with age - approximately 1 mL/min per year after age 30. So a 30-year-old with GFR 110 and a 75-year-old with GFR 65 may both be 'normal for age'. The CKD stages don't adjust for age, which is a known limitation; clinicians interpret GFR in age context. The 2021 formula and the proposed 'CKD-EPI 2021 RACE-FREE' have rapidly become the global standard, replacing prior MDRD-based equations.
Gelöste Beispiele
60-year-old female with diabetes, creatinine 1.4 mg/dL
CKD-EPI 2021: ≈ 44 mL/min/1.73m². Stage G3b - moderately to severely decreased. Requires nephrology referral, tight blood sugar control, blood pressure management, and potentially ACE inhibitor or ARB therapy. Risk of CKD progression is significant; preventive management is critical.
Wann GFR Calculator nutzen
- Annual kidney function screening for diabetics, hypertensives, and adults over 50.
- Drug dose adjustment - many medications require dose reduction at GFR below 60.
- Monitoring CKD progression over time - track quarterly creatinine and eGFR.
- Pre-surgery assessment for procedures requiring contrast dye or aminoglycoside antibiotics.
- Family screening when a first-degree relative has been diagnosed with CKD - genetic risk increases.
Häufige Fehler und Stolperfallen
- Using older formulas with race coefficients. CKD-EPI 2021 is the current standard.
- Ignoring single-test elevations. CKD diagnosis requires GFR <60 for ≥3 months. A single low reading may be from dehydration, acute illness, or recent meat-heavy meals.
- Forgetting that GFR naturally declines with age. A 75-year-old with GFR 75 isn't necessarily abnormal.
- Looking only at GFR. Albuminuria (urine protein) is the other key CKD marker - both should be checked.
- Self-medicating with NSAIDs (ibuprofen, diclofenac) when GFR is low. NSAIDs accelerate kidney damage.
Mehr aus diesem Tool herausholen
- Get serum creatinine and urine albumin tested annually if you have diabetes, hypertension, or family history of CKD.
- Avoid prolonged NSAID use if GFR is below 60. Paracetamol is generally safer for pain.
- If diabetic, aim for HbA1c under 7% to slow CKD progression.
- Hypertensives should target BP under 130/80 with ACE inhibitors or ARBs as first-line for kidney protection.
- Pair this calculator with the BMI, calorie and BMR calculators on this site for complete metabolic health planning. Consult a doctor for clinical interpretation.
Fragen zu GFR Calculator
What's a normal GFR?
≥90 mL/min/1.73m² is normal. GFR naturally declines ~1 mL/min per year after age 30, so a 70-year-old with GFR 70 is usually fine.
What are the CKD stages?
G1 (≥90, normal), G2 (60-89, mildly reduced), G3a (45-59), G3b (30-44), G4 (15-29, severe), G5 (<15, kidney failure / dialysis territory).
Why is the 2021 formula race-free?
The older formula included a 'race coefficient' for African-American patients, which the medical community recognised as scientifically unsupported. The 2021 update removes race entirely, using only creatinine, age and sex.
Should I use Cockcroft-Gault or CKD-EPI?
CKD-EPI 2021 is the modern standard for staging. Cockcroft-Gault is still used in some pharmacy/drug-dosing protocols (especially for older drugs).
What lowers GFR?
Diabetes, hypertension, chronic NSAID use, dehydration, kidney stones, autoimmune disease. Diabetes is the leading cause of CKD globally and in India.
When should I see a nephrologist?
If GFR is below 60 (Stage 3) for more than 3 months, or below 45 in a single test. Earlier referral is wise if GFR is dropping fast.
Track health metrics with care
Body composition, daily energy needs and pregnancy timelines all rest on formulas validated across millions of people, but no single number tells the whole story. The values from this calculator are point estimates with a known margin of error - body fat from skinfold or US Navy method has roughly a ±3% standard error compared to a DEXA scan, and BMR can vary ±10% person to person at the same height and weight. Use these numbers to track trends week over week, not to chase decimal precision day to day.
Pair this tool with the BMR, TDEE, calorie and macro calculators to turn a single measurement into an actionable plan. None of these tools are a substitute for a qualified doctor, registered dietitian or certified strength coach - but they remove the busywork so you spend more time on training and recovery, less on math.
The GFR Calculator is part of the Health & Fitness suite on Online Calculator Tools, alongside 6 related calculators. All tools share the same UI patterns, the same privacy-first rendering (nothing is sent to a server), and the same commitment to showing the formula and assumptions behind every result.