Free tool · Renal
Estimated glomerular filtration rate from serum creatinine, using the CKD-EPI 2021 race-free equation — with MDRD shown beside it, because a lot of reports still carry it and the gap is worth seeing.
The calculator
CKD-EPI 2021 is the headline number; MDRD sits beside it so you can see how far the two drift on the same inputs, and the KDIGO category is read off the result.
Everything is calculated in your browser. Nothing is sent anywhere, and nothing is stored.
Reference
The category is one of three axes. It says how much filtration is left, not what caused the loss and not how much protein is being spilled.
| Category | eGFR (mL/min/1.73 m²) | 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 | Under 15 | Kidney failure |
The arithmetic
eGFR = 142
× min(Scr/κ, 1)^α
× max(Scr/κ, 1)^-1.200
× 0.9938^age
× 1.012 (if female)
κ = 0.7 (female), 0.9 (male)
α = -0.241 (female), -0.302 (male)
Scr in mg/dLThis is the default result above, and the one to put on a report. The 2021 refit removed the race coefficient that earlier versions carried.
eGFR = 175
× Scr^-1.154
× age^-0.203
× 0.742 (if female)
Scr in mg/dLShown for comparison only. MDRD was fitted in a population with reduced filtration and is least reliable above 60, where it tends to read low — which is how an ordinary result becomes an unnecessary referral.
If you run the lab
If your technician is retyping a creatinine into a website to get an eGFR, that is a transcription step in the middle of a result — and transcription steps are where wrong numbers come from.
Questions, answered
CKD-EPI 2021. It is the current recommendation, it does not use a race coefficient, and it is more accurate than MDRD at higher filtration rates — which is exactly the range where MDRD tends to under-report and flag healthy people as reduced. This calculator uses CKD-EPI 2021 as the primary result and shows MDRD beside it for comparison.
Because the equation it uses does not have a race term. The 2021 CKD-EPI refit removed it deliberately: race is a social category rather than a biological measure of filtration, and the coefficient was systematically raising reported eGFR for Black patients and delaying referral. The MDRD figure shown here is calculated without the race coefficient for the same reason.
No. Neither CKD-EPI nor MDRD is validated under 18, and this calculator will tell you so rather than return a number. Paediatric estimation uses the bedside Schwartz equation, which needs the child's height as well as creatinine.
No. KDIGO staging is by cause, GFR category and albuminuria category together, and CKD requires the abnormality to have been present for more than three months. A single eGFR is one axis of three — useful, and not a diagnosis on its own.
mL/min/1.73 m². The estimate is indexed to a standard body surface area of 1.73 m² so that results are comparable between people of different sizes. For drug dosing at extremes of body size, absolute (de-indexed) GFR is sometimes preferred.
No. The calculation runs in your browser. There is no request to a server, nothing is stored, and no patient value is logged anywhere.
Yes. Calculated parameters can sit in a report template and compute from the entered result, so a creatinine result carries its eGFR without anyone opening a calculator. Report templates are configured with you during onboarding.
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