GFR Calculator
Estimate your Glomerular Filtration Rate (eGFR) from serum creatinine, age, and sex using the current race-free 2021 CKD-EPI equation, then see where it falls on the CKD staging scale.
CKD-EPI
2021 Formula
6
CKD Stages
Free
Educational Use
Calculate eGFR
Estimated GFR
79.3
mL/min/1.73 m²
G2 — Mildly DecreasedA mild reduction in filtration that is usually symptom-free and common with normal aging. It only counts as CKD when kidney damage markers are also present, or when it persists below 60 for three months or more.
Formula
CKD-EPI 2021
Function
66%
79.3 mL/min
eGFR
G2
CKD Stage
66%
Kidney Fn %
Mildly Decreased
Status
Your Creatinine, Both Units
1.10 mg/dL
Conventional
97.2 µmol/L
SI Unit
CKD Staging by eGFR (KDIGO Guidelines)
Understanding eGFR and Kidney Function
The Glomerular Filtration Rate (GFR) measures how many milliliters of blood your kidneys filter per minute, standardized to a body surface area of 1.73 m². It’s the single best overall indicator of kidney filtering capacity. Because directly measuring GFR requires an invasive clearance test, clinicians almost always work with an estimated GFR (eGFR) calculated from a routine blood test for serum creatinine, combined with age and sex.
This calculator uses the 2021 CKD-EPI Creatinine equation, the race-free version jointly recommended by the National Kidney Foundation and American Society of Nephrology. It replaced the older 2009 formula, which applied a separate multiplier for patients coded as Black — a population-level adjustment that could distort an individual result. The 2021 equation removes that variable entirely and uses the same math for every patient, based only on creatinine, age, and sex.
2021 CKD-EPI Creatinine Equation (Race-Free)
Female, Scr ≤ 0.7: eGFR = 142 × (Scr/0.7)^-0.241 × 0.9938^age × 1.012Female, Scr > 0.7: eGFR = 142 × (Scr/0.7)^-1.2 × 0.9938^age × 1.012Male, Scr ≤ 0.9: eGFR = 142 × (Scr/0.9)^-0.302 × 0.9938^ageMale, Scr > 0.9: eGFR = 142 × (Scr/0.9)^-1.2 × 0.9938^ageScr = serum creatinine in mg/dL. To convert from µmol/L, divide by 88.4 — this calculator does that conversion for you automatically.
⚠ Medical Disclaimer — Not a Diagnosis
eGFR is just one lab marker among several clinicians use to assess kidney function. A single reading does not diagnose chronic kidney disease (CKD) — that requires either an eGFR below 60 sustained for three months or more, or other markers of kidney damage such as albumin in the urine. This calculator is for educational purposes only. Always discuss your results with a doctor, and never self-diagnose or change medication based solely on this tool.
What Affects Your Creatinine Level
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Muscle Mass
Creatinine is a byproduct of muscle breakdown, so more muscular people naturally run higher and can be misread as having lower kidney function than they actually do.
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Diet
A large meat meal shortly before a blood draw can temporarily raise measured creatinine, independent of how well the kidneys are actually filtering.
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Hydration
Dehydration concentrates the blood and can push creatinine up; well-hydrated patients typically show a truer baseline reading.
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Medications
Some antibiotics, NSAIDs, and other drugs can raise creatinine readings without reflecting a real, lasting change in kidney filtration.
— FAQ