eGFR Calculator — CKD-EPI 2021 Kidney Function Estimator
Calculate your estimated GFR (eGFR) using the CKD-EPI 2021 equation (no race variable). Enter serum creatinine, age, and biological sex to get your kidney function stage (G1–G5 KDIGO) and a clinical recommendation.
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Reviewed by: Martín Rodríguez (editorial policy ) · Last reviewed:
Result
eGFR (mL/min/1.73m²)
eGFR ≈ 62 mL/min/1.73m² · Stage G2 Mild · Recommendation: Identify cause, monitor
CKD Stage
Clinical Recommendation
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Estimated GFR (eGFR) is the primary measure clinicians use to assess how well your kidneys filter waste from the blood. This calculator uses the CKD-EPI 2021 equation — the current gold-standard recommended by KDIGO and the National Kidney Foundation — which removed the race coefficient present in earlier versions. You only need your serum creatinine result (from a standard blood panel), your age, and your biological sex.
The CKD-EPI 2021 equation was published by Inker et al. in the New England Journal of Medicine (2021) and is now the standard adopted by KDIGO, NKF, and ASN. The 2021 revision eliminated the race variable that introduced systematic inequities in treatment access.
When to use this calculator
- Reviewing a lab report — your blood panel lists serum creatinine and you want to understand what it means for kidney function before your next appointment.
- Monitoring CKD progression — you have a known diagnosis and want to track how your eGFR changes over time as you adjust diet, medications, or blood pressure control.
- Pre-procedure risk assessment — surgeons and anesthesiologists use eGFR to gauge safe dosing of contrast agents and anesthetics that are renally cleared.
- Medication dose adjustment — many drugs (metformin, NSAIDs, certain antibiotics) require dose reduction or are contraindicated below specific eGFR thresholds.
CKD Stages by eGFR — KDIGO 2024
| Stage | eGFR (mL/min/1.73m²) | Description | Follow-up |
|---|---|---|---|
| G1 | ≥ 90 | Normal or high | Annual check |
| G2 | 60–89 | Mildly decreased | Identify cause, monitor |
| G3a | 45–59 | Mild-to-moderately decreased | Nephrology referral |
| G3b | 30–44 | Moderately-to-severely decreased | Active nephrology care |
| G4 | 15–29 | Severely decreased | Prepare for renal therapy |
| G5 | < 15 | Kidney failure | Dialysis or transplant |
Fuente: KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of CKD. Threshold for CKD diagnosis: eGFR < 60 mL/min/1.73m² persisting > 3 months.
How it works
What Is eGFR?
Glomerular Filtration Rate (GFR) measures how many millilitres of blood the kidneys' glomeruli filter per minute, normalized to a standard body surface area of 1.73 m². Because direct measurement requires injecting special tracers (inulin clearance), clinicians estimate it — hence the "e" in eGFR — using serum creatinine, age, and sex.
The CKD-EPI 2021 Equation
Published in the New England Journal of Medicine (Inker et al., 2021), this is the equation used by this calculator:
eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^(−1.200)
× 0.9938^Age × (1.012 if Female)Where:
The factor 0.9938^Age captures physiological GFR decline with aging (~0.62% per year after age 40).
CKD Stages and eGFR Reference Table (KDIGO 2024)
| Stage | eGFR (mL/min/1.73m²) | Description | Follow-up |
|---|---|---|---|
| G1 | ≥ 90 | Normal or high | Annual check |
| G2 | 60–89 | Mildly decreased | Identify cause, monitor |
| G3a | 45–59 | Mild-to-moderately decreased | Nephrology referral |
| G3b | 30–44 | Moderately-to-severely decreased | Active nephrology care |
| G4 | 15–29 | Severely decreased | Prepare for renal therapy |
| G5 | < 15 | Kidney failure | Dialysis or transplant |
Key threshold: eGFR < 60 mL/min/1.73m² for > 3 months = CKD diagnosis.
Typical eGFR by Age and Sex (Reference)
| Age | Male (avg eGFR) | Female (avg eGFR) |
|---|---|---|
| 25 years | ~120 mL/min/1.73m² | ~110 mL/min/1.73m² |
| 35 years | ~113 | ~103 |
| 45 years | ~106 | ~97 |
| 55 years | ~99 | ~90 |
| 65 years | ~91 | ~83 |
| 75 years | ~84 | ~76 |
Estimated at creatinine 0.9 mg/dL (male) / 0.7 mg/dL (female). eGFR declines ~1 mL/min/1.73m² per year after age 40.
Why Serum Creatinine?
Creatinine is a muscle waste product filtered almost entirely by the glomeruli. Its blood level rises predictably as filtration falls. Caveats: very muscular individuals may have higher baseline creatinine; sarcopenic or malnourished patients may have falsely low creatinine masking moderate CKD.
Limitations
Worked Example: 52-year-old female, creatinine 1.1 mg/dL
Inputs: creatinine = 1.1 mg/dL | age = 52 | sex = Female
Sex-specific constants: κ = 0.7, α = −0.241
Ratio = 1.1 / 0.7 = 1.571 → min(ratio, 1) = 1, max(ratio, 1) = 1.571
eGFR = 142 × (1)^(−0.241) × (1.571)^(−1.200) × (0.9938)^52 × 1.012
eGFR = 142 × 1 × 0.5985 × 0.7261 × 1.012 ≈ 62.4 → rounded to 62 mL/min/1.73m²
Stage: G2 Mild — eGFR 60–89 mL/min/1.73m² (mildly decreased function)
eGFR ≈ 62 mL/min/1.73m² · Stage G2 Mild · Recommendation: Identify cause, monitor
Disclaimer: Los resultados son orientativos y no reemplazan la consulta médica profesional. Antes de tomar decisiones con impacto, consultá con un médico, nutricionista o profesional de la salud matriculado.
Frequently asked questions
What is a normal eGFR for adults?
An eGFR of 90 mL/min/1.73m² or higher (Stage G1) is considered normal in adults with no other signs of kidney damage. eGFR naturally declines about 0.7–1 mL/min/1.73m² per year after age 40, so a healthy 75-year-old may have an eGFR of 65–75 without any kidney disease. The critical threshold is 60 mL/min/1.73m²: below this level for more than 3 months indicates Chronic Kidney Disease.
What is the CKD-EPI 2021 formula, and how does it differ from the 2009 version or MDRD?
CKD-EPI 2021 was published by Inker et al. in the New England Journal of Medicine (2021) following a NKF/ASN task force review. The 2021 update removed the race coefficient that was in the 2009 CKD-EPI equation — a 1.159 multiplier for Black patients that introduced systematic inequities in treatment access. The 2021 equation uses only creatinine, age, and biological sex, and demonstrates comparable or superior accuracy across all populations. Compared to MDRD, CKD-EPI 2021 is significantly more accurate when eGFR is above 60 mL/min/1.73m², which is the most clinically important range for early CKD detection.
My lab report already shows an eGFR — why use this calculator?
Many labs still report eGFR using the 2009 CKD-EPI or MDRD formula. If you want to confirm your value under CKD-EPI 2021 (without a race coefficient), or your lab used a different method, this calculator lets you recalculate using the current standard. It also provides your KDIGO stage (G1–G5) and a practical clinical recommendation that most lab reports omit.
Can a single low eGFR reading diagnose chronic kidney disease?
No. KDIGO defines CKD as kidney abnormalities present for more than 3 months. A single low eGFR could reflect dehydration, acute illness, heavy exercise, high protein intake before the blood draw, or medications like trimethoprim or cimetidine that transiently raise creatinine without real kidney damage. Your doctor will typically confirm with at least two values 3 months apart, plus urinalysis (looking for proteinuria) and possibly imaging.
How does biological sex affect the eGFR calculation?
Women typically have lower muscle mass than men, producing less creatinine at baseline. At the same serum creatinine level, a woman will have a higher eGFR than a man. CKD-EPI 2021 accounts for this with sex-specific constants: κ = 0.7 for females vs. 0.9 for males, and α = −0.241 vs. −0.302, plus a 1.012 multiplier for females.
What factors can temporarily lower eGFR without true kidney disease?
Dehydration (reduces kidney blood flow), intense exercise before the blood draw, high-protein meals, NSAIDs (ibuprofen, naproxen) taken 24–48 hours before the test, and ACE inhibitors/ARBs (which cause a functional, usually benign, drop in eGFR when first started). Always tell your doctor about medications and recent diet before a kidney function test.
At what eGFR should I see a nephrologist?
Most guidelines recommend referral to a nephrologist when eGFR falls below 45 mL/min/1.73m² (Stage G3a/G3b boundary), or earlier if there is: rapid decline (>5 mL/min/1.73m² per year), significant proteinuria (urine albumin > 300 mg/g), difficult-to-control hypertension, or suspected rare kidney disease. Stage G4 (eGFR 15–29) requires active preparation for renal replacement therapy (dialysis or transplant evaluation).
What medications must be dose-adjusted or avoided at low eGFR?
Key drugs requiring adjustment: Metformin (use cautiously below eGFR 45, contraindicated below 30); NSAIDs like ibuprofen/naproxen (generally avoid below eGFR 60 in CKD); Gadolinium MRI contrast (nephrogenic systemic fibrosis risk below eGFR 30); Iodinated CT contrast (careful assessment and hydration below eGFR 45); many antibiotics (aminoglycosides, vancomicin) require dose adjustments. Always inform any prescriber of your current eGFR.
Is eGFR from creatinine accurate in all patients?
Not always. Serum creatinine reflects muscle mass, so results can be misleading in amputees, bodybuilders, individuals with severe malnutrition, and during pregnancy. For these cases, cystatin C — a protein filtered independently of muscle mass — offers a more accurate eGFR. Some labs now report cystatin-C-based eGFR or the CKD-EPI combined creatinine-cystatin C equation alongside the creatinine-based value.
Does diet or exercise affect eGFR over time?
Yes. Chronic high-protein diets increase creatinine production and glomerular pressure, which can hasten CKD progression. In CKD patients, dietary protein restriction (typically 0.6–0.8 g/kg/day under dietitian supervision) is shown to slow decline. Regular moderate aerobic exercise improves cardiovascular risk — a key driver of CKD progression — without harming the kidneys, though it may transiently raise creatinine right after intense workouts.
What is the difference between acute kidney injury (AKI) and chronic kidney disease (CKD)?
Acute kidney injury is a sudden drop in kidney function over hours or days, often reversible (caused by severe dehydration, infections, nephrotoxic drugs, or obstruction). CKD is a slow, progressive loss of kidney function over at least 3 months, generally irreversible. This calculator estimates a point-in-time eGFR but cannot distinguish AKI from CKD — for that you need clinical context and comparison with previous values. A sudden drop in eGFR compared to prior readings is a medical emergency.
How do diabetes and hypertension damage kidney function (GFR)?
Diabetes causes diabetic nephropathy by damaging the small blood vessels of the glomerulus, initially detected only by microalbuminuria (before eGFR falls). Hypertension causes sustained hyperfiltration that progressively damages renal tissue. When both coexist, damage accelerates significantly. Together, diabetes and hypertension account for approximately 60% of new dialysis cases annually in most countries. This is why measuring eGFR and albuminuria in every patient with these conditions is critical, even if they feel well.
When is a low eGFR a medical emergency?
Seek emergency care (same day) if: eGFR has dropped suddenly compared to recent values, you have very little or no urine output, visible blood in urine, significant swelling of face or legs, difficulty breathing, or mental confusion — these may indicate acute kidney injury or severe decompensation. See your doctor within days (not emergency) if: eGFR is below 60 for the first time without a prior diagnosis, or values are consistently declining between tests.
Sources & references
Methodology & trust
Editorial
Calculadora de salud revisada por el equipo editorial de Hacé Cuentas, contrastada con NKF/ASN Task Force — New Creatinine- and Cystatin C–Based Equations (CKD-EPI 2021), NEJM 2021, según nuestra política editorial y metodología.
Updates
Última revisión: June 20, 2026. Los parámetros se verifican periódicamente con las fuentes citadas.
Privacy
Calculations run 100% in your browser. We do not store or transmit your data.
Limitations
Indicative results. For critical decisions, consult a professional.
📌 How to cite this calculator
Rodríguez, M. (2026). eGFR Calculator — CKD-EPI 2021 Kidney Function Estimator. Hacé Cuentas. https://hacecuentas.com/gfr-glomerular-filtration-rate-ckd-epi
Contenido bajo licencia CC-BY 4.0 — reutilizable citando la fuente con enlace a Hacé Cuentas.