eGFR Calculator

Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer Last updated: August 20, 2026

Disclaimer: This calculator is provided for informational and educational purposes only and does not constitute financial, medical, legal, or other professional advice. Always consult a qualified professional before making decisions based on these results.

📚 Confused about how this is calculated? Read the full The Waste Product That Doubles as a Kidney Gauge →

Estimating Kidney Function From a Single Blood Value

Serum creatinine on its own is a poor guide to kidney function. It is a waste product of muscle metabolism, so a frail 80-year-old and a muscular 30-year-old can share an identical creatinine reading while their kidneys are doing very different amounts of work. The estimated glomerular filtration rate corrects for that by folding age and sex into the calculation, producing a figure that speaks to filtration capacity rather than to muscle mass. This calculator implements the CKD-EPI 2021 creatinine equation — the race-free revision that replaced the earlier version carrying a Black-race coefficient.

The Formula

The CKD-EPI 2021 creatinine equation, exactly as this calculator applies it:

eGFR = 142 × min(Scr ÷ κ, 1)^α × max(Scr ÷ κ, 1)^−1.200 × 0.9938^Age × 1.012 (if female)

κ = 0.7 (female) or 0.9 (male)
α = −0.241 (female) or −0.302 (male)
Scr = serum creatinine in mg/dL

The two-part min/max structure is what gives the equation its kink: below the sex-specific κ threshold, creatinine changes eGFR gently; above it, the steep −1.200 exponent takes over and eGFR falls away quickly. That deliberate asymmetry is why a creatinine rise from 1.0 to 1.4 costs far more filtration than a rise from 0.6 to 1.0.

eGFR Across Age, Sex and Creatinine

Every figure in this table was produced by running the equation above:

eGFR in mL/min/1.73m² by serum creatinine, age and sex (CKD-EPI 2021)
Serum creatinine	Male, 30	Female, 30	Male, 50	Female, 50	Male, 70	Female, 70
0.8 mg/dL	122.1	101.6	107.8	89.7	95.2	79.2
1.0 mg/dL	103.8	77.7	91.7	68.6	81.0	60.6
1.4 mg/dL	69.3	51.9	61.2	45.8	54.1	40.5
2.0 mg/dL	45.2	33.8	39.9	29.9	35.2	26.4
3.0 mg/dL	27.8	20.8	24.5	18.4	21.7	16.2

Note the column pairs: at the same creatinine, the female estimate is consistently lower, reflecting the lower κ and the fact that a given creatinine represents proportionally more filtration burden at typically lower muscle mass.

Why the Result Says "per 1.73m²"

eGFR is reported normalised to a body surface area of 1.73 m² — a figure adopted decades ago as a stand-in for an average adult. It makes results comparable between a small patient and a large one, at the cost of being slightly wrong for anyone far from that reference size. When absolute clearance matters more than comparability, the Cockcroft-Gault creatinine clearance is often used instead, precisely because it is not surface-area normalised.

CKD Stages by GFR

The KDIGO GFR categories are the standard published bands used to describe filtration:

KDIGO GFR categories (G1–G5)
Category	GFR (mL/min/1.73m²)	Description
G1	90 and above	Normal or high
G2	60–89	Mildly decreased
G3a	45–59	Mildly to moderately decreased
G3b	30–44	Moderately to severely decreased
G4	15–29	Severely decreased
G5	Below 15	Kidney failure

These bands are published reference categories included here for context. This calculator returns an eGFR value only; it does not assign a stage, and a stage cannot be assigned from one reading in any case.

Note: eGFR is an estimate, and it is educational reference material here — not a diagnosis. A single value cannot establish chronic kidney disease, which by definition requires abnormality persisting over at least three months alongside other findings. Discuss any real laboratory result with a healthcare professional.

Where This Estimate Gets Used

Drug dosing thresholds — a great many medications carry renal dose adjustments keyed to eGFR bands.
Contrast and procedure planning — imaging protocols routinely reference recent eGFR.
Longitudinal monitoring — the trend across repeated measurements carries more information than any single value.
Understanding lab reports — eGFR is auto-calculated on most creatinine panels, and knowing the inputs demystifies why it moved.

How to Use This Calculator

Enter Age (years).
Enter Serum Creatinine (mg/dL). If your lab reports in µmol/L, divide by 88.4 to convert.
Select Sex — this sets both κ and α, and applies the 1.012 female multiplier.
Select Calculate. The output shows the eGFR along with each intermediate term, so you can see which factor is driving the result.

Related Calculations

Compare against the Creatinine Clearance Calculator, which uses Cockcroft-Gault and weight rather than surface-area normalisation, or work out the 1.73 m² reference itself with the Body Surface Area Calculator.

Principles of Glomerular Filtration Rate (eGFR) and CKD Staging

An estimated Glomerular Filtration Rate (eGFR) calculator computes kidney filtration efficiency normalized to standard body surface area (mL/min/1.73m²). In clinical nephrology, eGFR serves as the universal diagnostic biomarker for detecting, diagnosing, and staging Chronic Kidney Disease (CKD) under international KDIGO clinical practice guidelines.

The CKD-EPI 2021 Race-Free Creatinine Equation

eGFR = 142 · min( S_cr / κ, 1 )^α · max( S_cr / κ, 1 )^-1.200 · 0.9938^Age · [ 1.012 if Female ]
Where κ = 0.70 (Females) or 0.90 (Males) | α = -0.241 (Females) or -0.302 (Males)

KDIGO Chronic Kidney Disease (CKD) Classification Stages

CKD Stage	eGFR Range (mL/min/1.73m²)	Clinical Description & Nephrology Action
Stage G1	≥ 90	Normal or high kidney function (CKD diagnosed only if kidney damage/proteinuria is present)
Stage G2	60 to 89	Mildly decreased kidney function
Stage G3a	45 to 59	Mild-to-moderate kidney impairment; cardiovascular risk monitoring
Stage G3b	30 to 44	Moderate-to-severe impairment; medication dose adjustment
Stage G4	15 to 29	Severely decreased function; prepare for renal replacement therapy
Stage G5	< 15	Kidney Failure (End-Stage Renal Disease ESRD) — Dialysis / Kidney Transplant Required

Step-by-Step Worked Calculation Example

Example: Calculating eGFR for a 55-Year-Old Male Patient

Problem: A 55-year-old male presents with Serum Creatinine S_cr = 1.35 mg/dL. Calculate: (1) eGFR using the CKD-EPI 2021 formula; and (2) Identify the corresponding KDIGO CKD Stage.

Step 1: Calculate eGFR:

For males (κ = 0.90): S_cr / κ = 1.35 / 0.90 = 1.50 (greater than 1.0)

eGFR = 142 × (1.0)^-0.302 × (1.50)^-1.200 × (0.9938)⁵⁵ = 142 × 1.0 × 0.6139 × 0.7101 = 61.90 mL/min/1.73m²

Conclusion: An eGFR of 62 mL/min places the patient in Stage G2 (Mildly Decreased), requiring blood pressure and urinary albumin monitoring.

Serum Cystatin C as a Confirmatory Biomarker

In clinical scenarios where muscle mass or dietary protein distorts serum creatinine (amputees, bodybuilders, severe liver cirrhosis):

Nephrologists measure Serum Cystatin C (a non-creatinine protein produced by all nucleated cells), utilizing the combined CKD-EPI Creatinine-Cystatin C Equation to definitively confirm borderline eGFR diagnoses.

SGLT2 Inhibitor Renoprotection in CKD

Landmark clinical trials (DAPA-CKD, EMPA-KIDNEY) demonstrate that SGLT2 inhibitors significantly slow eGFR decline in CKD patients with eGFR down to 20 mL/min/1.73m², delaying end-stage kidney failure by years.

Kidney Disease Prevention

Regular annual eGFR monitoring in diabetic and hypertensive patients enables early therapeutic interventions that preserve remaining renal nephron architecture.

Long-Term Renal Health

Adopting low-sodium nutrition, maintaining tight glycemic control, and avoiding nephrotoxic NSAID pain medications preserves glomerular filtration architecture and sustains lifelong kidney health.

Renal Function Preservation

Early detection of eGFR decline enables clinical interventions that slow chronic kidney disease progression.