eGFR Calculator (CKD-EPI 2021)

Overview

The eGFR Calculator estimates your glomerular filtration rate — how well your kidneys filter waste — from serum creatinine, age, and sex, and maps the result to KDIGO kidney function stages (G1–G5). It uses the CKD-EPI 2021 race-free equation published by the NKF/ASN task force, now the standard in laboratories worldwide. Use it to interpret the creatinine or eGFR value on your health checkup report.

Formula

CKD-EPI 2021: eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^(−1.200) × 0.9938^age × 1.012 (if female)

- Scr: serum creatinine (mg/dL)
- κ: 0.7 (female), 0.9 (male)
- α: −0.241 (female), −0.302 (male)
- Unit: mL/min/1.73㎡ (BSA-adjusted)

KDIGO stages: G1 ≥90 / G2 60–89 / G3a 45–59 / G3b 30–44 / G4 15–29 / G5 <15

Example: 50-year-old male, creatinine 1.0 mg/dL → eGFR 91.7 → G1 (normal or high)

How to Use

1. 1Select your sex — the equation uses different κ and α coefficients for males and females.
2. 2Enter your age (adults 18+ only).
3. 3Enter serum creatinine in mg/dL from your lab report; divide by 88.4 if your report uses µmol/L.
4. 4Check the eGFR and KDIGO stage; values under 60 warrant a nephrology consultation.

Examples

Background

GFR — the volume of blood the glomeruli filter per minute — is the standard measure of kidney function. Because serum creatinine, a muscle metabolite cleared only by the kidneys, is influenced by muscle mass, age, and sex, clinical practice uses equation-adjusted estimates (eGFR). The CKD-EPI 2021 equation removed the race coefficient from the 2009 version and was published by the NKF/ASN task force. KDIGO guidelines define chronic kidney disease as eGFR below 60 or markers of kidney damage (such as albuminuria) persisting for more than 3 months.

Tips

• ✔A single reading can fluctuate with hydration, meat intake, or intense exercise — the trend matters more than one value.
• ✔Even with eGFR above 60, albuminuria can indicate CKD; review your urine test together.
• ✔People with diabetes or hypertension should check creatinine and urine albumin annually.
• ✔With extreme muscle mass (bodybuilders, sarcopenia, amputation), consider a cystatin C-based equation for accuracy.

FAQ