eGFR Calculator
Estimate your glomerular filtration rate (eGFR) from serum creatinine, age and sex using the race-free CKD-EPI 2021 equation — with mg/dL or µmol/L input and the matching KDIGO GFR category (G1–G5). Runs locally in your browser. Informational only, not a diagnosis.
About this eGFR calculator
This tool estimates your glomerular filtration rate (eGFR) — a measure of how well your kidneys filter waste from your blood — from a serum creatinine lab value, your age and your sex. It uses the CKD-EPI creatinine equations, the standard used by clinical laboratories, and reports the result in mL/min/1.73 m² along with the matching KDIGO GFR category (G1–G5). Everything runs locally in your browser; nothing you enter is uploaded.
By default it uses the CKD-EPI 2021 creatinine equation, the current race-free standard recommended by the National Kidney Foundation and the American Society of Nephrology. You can also select the older CKD-EPI 2009 equation for comparison — provided here in its race-free form, with the 2009 race coefficient deliberately omitted, in line with the 2021 guidance.
Enter creatinine in mg/dL (US) or µmol/L (SI); µmol/L is converted to mg/dL by dividing by 88.42 before the equation is applied.
Worked example
Enter creatinine 1.0 mg/dL, age 50, sex male, equation CKD-EPI 2021:
{
"egfr": 92.0,
"unit": "mL/min/1.73 m²",
"equation": "ckd_epi_2021",
"creatinine_mg_dl": 1.0,
"age": 50.0,
"sex": "male",
"gfr_stage": "G1",
"stage_description": "Normal or high",
"summary": "eGFR 92 mL/min/1.73 m² (CKD-EPI 2021) — GFR category G1 (Normal or high)"
}
The 2021 equation gives 142 × (1.0/0.9)^−1.200 × 0.9938^50 ≈ 92 mL/min/1.73 m², which falls in
the G1 band (≥90). A 60-year-old female with a creatinine of 1.2 mg/dL instead returns
about 52 mL/min/1.73 m² — the G3a band.
KDIGO GFR categories
| Category | eGFR (mL/min/1.73 m²) | Meaning |
|---|---|---|
| G1 | ≥ 90 | 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 | < 15 | Kidney failure |
A G1 or G2 eGFR is in the normal range on its own — chronic kidney disease is only diagnosed in those bands when there is also a marker of kidney damage (such as albuminuria) present for at least three months.
Limits & notes
- Informational estimate, not a diagnosis or medical advice. eGFR is an estimate; only a clinician can interpret it alongside your full history. Do not change any treatment based on this tool.
- Adults only. CKD-EPI is validated for people 18 and over; ages under 18 are rejected — a pediatric equation (Schwartz / CKiD) is a different calculation.
- The creatinine value should be IDMS-standardized (as reported by modern labs). A single creatinine is a snapshot; eGFR can shift with hydration, muscle mass, diet and lab timing.
- Cystatin-C equations (2012 cystatin C, 2021 creatinine + cystatin C) need a cystatin C lab value and are not included here — this is a creatinine-only calculator.
- Race is not used. The default 2021 equation is race-free, and the 2009 option omits the race coefficient.
FAQ
What is eGFR and what is a normal value?
eGFR (estimated glomerular filtration rate) estimates how many millilitres of blood your kidneys filter per minute, normalized to a standard body size (1.73 m²). A value of 90 or above is considered normal or high (category G1). Values fall gradually with age even in healthy people. On its own a normal eGFR doesn't rule out early kidney disease, and a single low value doesn't confirm it — trends over months matter more than one reading.
Why does this calculator not use race?
In 2021 a National Kidney Foundation / American Society of Nephrology task force recommended against including race in eGFR equations. This tool uses the race-free CKD-EPI 2021 equation by default, and when you pick the older 2009 equation it is applied in its race-free form (the 2009 race coefficient is left out). You get the same estimate regardless of race.
Should I enter creatinine in mg/dL or µmol/L?
Use whichever unit your lab report shows. US reports are usually in mg/dL; many other countries report in µmol/L (SI). Pick the matching unit and the tool converts internally (µmol/L ÷ 88.42 = mg/dL). For example, 1.0 mg/dL ≈ 88.4 µmol/L.
What's the difference between the 2021 and 2009 equations?
Both estimate eGFR from creatinine, age and sex. The 2021 equation is the current recommended standard and is race-free by design. The 2009 equation is older and originally included a race coefficient; here it is offered only for historical comparison and in its race-free form. The two give slightly different numbers for the same inputs — for most people the 2021 result is what clinical labs now report.
Can I use this for a child?
No. The CKD-EPI equations are validated for adults (18 and older), so the tool rejects ages under 18. Estimating GFR in children uses a different equation (such as the bedside Schwartz or CKiD formula) based on height and creatinine.
Is my data sent anywhere?
No. The calculation runs entirely in your browser via WebAssembly. Nothing you enter is uploaded, logged or stored — reload the page and it's gone.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool egfr-calc 'creatinine=1.0'New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/egfr-calc/?creatinine=1.0&creatinine_unit=mg%2FdL&age=50&sex=male&equation=ckd_epi_2021Machine-readable descriptor: tool.json — title + parameters JSON Schema for agents.