GFR Calculator
Estimate your Glomerular Filtration Rate (eGFR) using the CKD-EPI 2021 race-free equation and MDRD formula to assess kidney function.
| Stage | eGFR Range | Description |
|---|---|---|
| G1 | ≥ 90 | Normal or high kidney function |
| 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 |
Estimate your kidney function (eGFR) from a blood creatinine level, using the current race-free CKD-EPI 2021 equation alongside the older MDRD formula for reference.
How GFR Calculator Works
CKD-EPI 2021 — the equation this calculator leads with, and the current standard recommended by the National Kidney Foundation and American Society of Nephrology — estimates eGFR from serum creatinine, age, and sex using a formula with different coefficients depending on whether your creatinine falls above or below a sex-specific threshold. Unlike its predecessor, it does not include a race adjustment.
The older MDRD formula (186 × creatinine^−1.154 × age^−0.203, adjusted for sex and, in its original form, race) is shown alongside for reference only — it is included because some older lab reports and clinical records still cite it, but CKD-EPI 2021 is now the preferred equation in current clinical guidelines.
Your result is classified into one of six CKD (Chronic Kidney Disease) stages, from G1 (normal or high function, eGFR ≥ 90) down to G5 (kidney failure, eGFR < 15), each with different monitoring and management implications.
See It In Action
Who Uses GFR Calculator and Why
- Understanding an eGFR value that appeared on a recent lab report by seeing which CKD stage it falls into.
- Comparing a result under the current CKD-EPI 2021 equation against the older MDRD formula that may appear on older records.
- Getting general context on kidney function trends before a follow-up conversation with a healthcare provider.
Mistakes to Avoid
- Treating a single eGFR reading as a diagnosis — a formal CKD diagnosis generally requires at least two abnormal readings at least three months apart along with other clinical context, not one calculator result.
- Comparing an eGFR calculated here directly against an old MDRD-based lab value without noting which formula was used — the two equations can diverge meaningfully for the same person.
- Not accounting for the fact CKD-EPI 2021 removed the race-based adjustment used in older versions, which can explain why an older report's number looks different from this calculator's result.
Tips for Best Results
- Use CKD-EPI 2021 as your primary reference, since it's the current standard recommended by the National Kidney Foundation and American Society of Nephrology — treat the MDRD figure as historical context only.
- If your result falls outside the normal range (under 60), bring it to a healthcare provider rather than interpreting it alone — they can order repeat testing and check other markers like proteinuria.
Fixing Common Problems
My eGFR here doesn't match what's on an older lab report. — Older reports sometimes used the MDRD formula, which for the same creatinine value can produce a meaningfully different number than the current CKD-EPI 2021 equation this calculator leads with — check which formula the lab report cites.
Terms Explained
eGFR (estimated Glomerular Filtration Rate): An estimate of how well the kidneys filter blood, calculated from serum creatinine along with age and sex.
CKD stage: One of six categories (G1 through G5) that classify kidney function based on eGFR, from normal function down to kidney failure.