The eGFR Calculator estimates the glomerular filtration rate to assess your kidney function.
Uses the CKD-EPI 2021 (race-free) formula based on serum creatinine, age, and sex. Results are classified into 6 stages of chronic kidney disease (G1-G5).
Disclaimer: Results are not a medical diagnosis. Consult a nephrologist for kidney function evaluation.
Calculator information
📋 How to use this calculator
- Enter serum creatinine from your most recent lab report (in mg/dL). Convert from umol/L by dividing by 88.4.
- Enter your age in whole years (minimum 18). CKD-EPI 2021 is validated for adults.
- Select biological sex (male or female), which affects the equation coefficients.
- Click Calculate to see estimated glomerular filtration rate in mL/min/1.73 m^2.
- Review the G1-G5 staging to interpret your kidney function.
- Consult your primary-care physician or a nephrologist if eGFR is below 60 mL/min/1.73 m^2 for three months. Tip: stay well hydrated before lab draws so creatinine is not skewed by dehydration.
🧮 CKD-EPI 2021 (race-free)
eGFR = 142 * min(Scr/k, 1)^a * max(Scr/k, 1)^-1.200 * 0.9938^Age * (1.012 if female)
- Scr = serum creatinine (mg/dL)
- k = 0.7 for females, 0.9 for males
- a = -0.241 for females, -0.302 for males
- Age = age in years
This NKF/ASN 2021 equation replaces the 2009 version by removing the race coefficient.
💡 Worked example: 55-year-old man, creatinine 1.2 mg/dL
Given:- Scr = 1.2 mg/dL
- Age = 55 years
- Sex = male
- k = 0.9, a = -0.302
Steps:- Scr/k = 1.2 / 0.9 = 1.333
- min(1.333, 1) = 1; max(1.333, 1) = 1.333
- eGFR = 142 * 1^(-0.302) * 1.333^(-1.200) * 0.9938^55
- eGFR = 142 * 1 * 0.715 * 0.711 = 72.2 mL/min/1.73 m^2
Result: eGFR of 72 mL/min/1.73 m^2 falls in stage G2 (mildly decreased), still within an acceptable range of kidney function.
❓ Frequently asked questions
What do CKD stages G1 through G5 mean?
G1 (>= 90) is normal function, G2 (60-89) is a mild decrease, G3a (45-59) is mild-to-moderate, G3b (30-44) is moderate-to-severe, G4 (15-29) is severe, and G5 (<15) is kidney failure. A CKD diagnosis requires either eGFR < 60 or another marker of kidney damage (proteinuria, hematuria) persisting for >= 3 months.
Why did CKD-EPI 2021 remove the race coefficient?
Earlier versions added a 1.159 multiplier for Black patients, but race is a social construct rather than a biological variable. In 2021 the NKF and ASN recommended a race-free formula to avoid overestimating eGFR and delaying CKD diagnosis in certain populations.
Is eGFR accurate for everyone?
No. eGFR is less reliable in people with extreme muscle mass (bodybuilders, amputees), pregnancy, malnutrition, strict vegan diets, or those under 18. In such cases clinicians often use cystatin C, a 24-hour creatinine clearance, or iohexol clearance as the gold standard.
How much does a creatinine test cost in the U.S.?
A serum creatinine test at retail labs (Labcorp, Quest) typically costs $10-$40 cash-pay, or as part of a basic metabolic panel for $30-$80. With most insurance plans it is covered with little or no out-of-pocket cost when medically indicated. Annual testing is recommended for people with diabetes, hypertension, or age over 60.
What should I do if my eGFR is low?
If eGFR is < 60 for three months, see your primary-care physician or a nephrologist. Keep blood pressure < 130/80, control blood glucose if diabetic, avoid NSAIDs such as ibuprofen and diclofenac, limit protein to 0.6-0.8 g/kg/day, and keep sodium under 2,300 mg/day. The CDC estimates that more than 1 in 7 U.S. adults (about 35.5 million) have CKD, and most are unaware of it.
📚 Sources & references
Last updated: May 11, 2026