- Choose Conventional (mg/dL) or SI (µmol/L) units to match the laboratory report. Switching units clears the creatinine field.
- Select biological sex and enter age in years.
- Enter the steady-state serum creatinine — not a value drawn during acute illness or rapidly changing kidney function.
- The result updates live: eGFR in mL/min/1.73 m², the CKD GFR category (G1–G5), and a plain-language interpretation with suggested next steps.
All computation runs in your browser; no values are stored or transmitted.
When to Use
Use this tool to estimate glomerular filtration rate (eGFR) from a steady-state serum creatinine in any adult being screened for, or followed with, chronic kidney disease. The CKD-EPI 2021 creatinine equation is the race-free standard endorsed by KDIGO and adopted across U.S. and international laboratories. The resulting eGFR — together with albuminuria — defines the KDIGO GFR category (G1–G5) used for staging, drug review, and referral decisions.
Appropriate population
Adults (≥18 years) with a stable, steady-state serum creatinine. Most useful for CKD screening and staging, tracking kidney function over time, dosing drugs that specify GFR thresholds, and deciding on nephrology referral or imaging-contrast precautions. The 2021 equation removes the prior Black-race coefficient and applies to all patients regardless of race or ethnicity.
When NOT to rely on it
Do not use during acute kidney injury or any non-steady state (creatinine still rising or falling). Creatinine-based eGFR is unreliable at extremes of muscle mass (amputees, bodybuilders, severe sarcopenia, cachexia, paraplegia), in pregnancy, and with high-meat or creatine-supplement intake. For drug dosing that the label specifies by creatinine clearance, use Cockcroft-Gault instead. When precision matters near a decision threshold, confirm with a cystatin C-based estimate (CKD-EPI 2021 creatinine–cystatin C) or measured GFR.
Pearls & Pitfalls
Stage with G and A together
An eGFR is only half of a CKD stage. Always pair the GFR category with a urine albumin-to-creatinine ratio (A1–A3); a patient with eGFR 50 and heavy albuminuria has a far worse prognosis than one with the same eGFR and no albuminuria.
Confirm near thresholds with cystatin C
When the eGFR sits near a decision point (drug eligibility, transplant listing, GFR 60), the CKD-EPI 2021 creatinine–cystatin C equation is more accurate than creatinine alone and is less affected by muscle mass. KDIGO 2024 suggests confirming with cystatin C when an accurate estimate will change management.
Pitfalls
(1) Never apply this equation during AKI or any non-steady state — the estimate lags real GFR. (2) Extremes of muscle mass distort creatinine-based eGFR: it overestimates GFR in cachexia and amputees and underestimates it in muscular individuals. (3) Do not use eGFR for drug doses the label specifies by creatinine clearance — use Cockcroft-Gault. (4) The equation is not validated in pregnancy or in children.
Why Use It
Serum creatinine alone is a poor index of kidney function because it varies with age, sex, and muscle mass. The CKD-EPI 2021 equation converts creatinine into an estimated GFR standardized to 1.73 m² of body-surface area, allowing consistent staging and comparison over time. Removing the race coefficient eliminated a source of systematic bias that previously assigned higher eGFR values to Black patients, which could delay specialist referral and transplant evaluation. A reliable eGFR underpins CKD staging, complication screening, contrast and drug safety, and the decision of when to plan kidney replacement therapy.
eGFR Calculator — CKD-EPI 2021 (race-free)
Enter the patient's most recent steady-state serum creatinine with age and sex to estimate GFR and the corresponding CKD GFR category. Switch units to match the laboratory report.
⚕ This calculator is for educational purposes only. eGFR alone does not determine CKD stage — albuminuria, blood pressure, and clinical history are also required. Always interpret in clinical context.
Next Steps
Use the result to support — not replace — clinical judgment.
- Interpret the value against the targets shown in the calculator and the Evidence section below, in the context of the full clinical picture.
- Trend serial measurements rather than acting on a single result; confirm abnormal or unexpected values before changing management.
- Apply the relevant KDIGO / specialty-guideline threshold and document the indication.
- Escalate or refer to nephrology when results are out of range, rapidly changing, or discordant with the clinical picture — and discuss the implications with the patient.
Evidence & References
Formula & Equations
The CKD-EPI 2021 creatinine equation has the general form eGFR = 142 × min(Scr/κ, 1)α × max(Scr/κ, 1)−1.200 × 0.9938Age × 1.012 [if female], where Scr is serum creatinine in mg/dL.
| Term | Value |
|---|---|
| κ (kappa) | 0.7 (female), 0.9 (male) |
| α (alpha) | −0.241 (female), −0.302 (male) |
| Female multiplier | 1.012 (applied only to women) |
| Age term | 0.9938 raised to the age in years |
| SI conversion | Scr (mg/dL) = Scr (µmol/L) ÷ 88.4 |
KDIGO GFR categories
| Category | eGFR (mL/min/1.73 m²) | Description |
|---|---|---|
| G1 | ≥ 90 | Normal or high (CKD only if other markers of damage) |
| 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 |
The 2021 equation contains no race coefficient. GFR category alone does not equal CKD stage — KDIGO staging combines the GFR (G) category with the albuminuria (A1–A3) category and requires chronicity (>3 months).
Evidence & References
The CKD-EPI 2021 creatinine equation was developed and validated by Inker and colleagues to estimate GFR without a race variable, and is the equation recommended by the KDIGO 2024 CKD guideline and a joint NKF–ASN task force for U.S. laboratories. It refits the 2009 CKD-EPI model on pooled development cohorts, removing the Black-race coefficient while preserving accuracy.
- Inker LA, Eneanya ND, Coresh J, et al. New Creatinine- and Cystatin C–Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385(19):1737–1749.
- Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314.
- Delgado C, Baweja M, Crews DC, et al. A Unifying Approach for GFR Estimation: Recommendations of the NKF-ASN Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease. Am J Kidney Dis. 2022;79(2):268–288.
- Levey AS, Stevens LA, Schmid CH, et al. A New Equation to Estimate Glomerular Filtration Rate (CKD-EPI). Ann Intern Med. 2009;150(9):604–612.
