eGFR Calculator: CKD-EPI 2021 (Race-Free)

1. Choose your sex. Sex sets the kappa and alpha coefficients and the female multiplier in the equation. Race is not an input.
2. Enter your age in years. This adult equation applies to ages 18 and older. Children and teens use a separate pediatric equation.
3. Enter your serum creatinine. Use the figure from your blood test. Pick mg/dL or umol/L; the tool converts umol/L by dividing by 88.4.

This is an educational estimate. It is not medical advice or a diagnosis.

GFR is the glomerular filtration rate, the volume of blood the kidneys filter each minute. It is the main measure of kidney function. Measuring the true rate is complex, so clinicians estimate it from a blood test, and that estimate is called eGFR.

The result is reported in millilitres per minute per 1.73 square metres of body surface area, written mL/min/1.73 m2. The 1.73 m2 adjusts the rate to a standard adult body size.

This calculator uses serum creatinine, a waste product that healthy kidneys clear from the blood. When filtration falls, creatinine rises, so a higher creatinine gives a lower eGFR for the same age and sex.

The National Kidney Foundation uses eGFR with any markers of kidney damage to place a person in a GFR category from G1 to G5. The number is an estimate for a population, not a direct measurement for one person.

The calculator applies the CKD-EPI 2021 creatinine equation exactly as the National Kidney Foundation and the NIDDK publish it. This 2021 equation is race-free.

1. Normalise creatinine. Divide serum creatinine in mg/dL by K, which is 0.7 for women and 0.9 for men.
2. Apply the two power terms. Raise the smaller of that ratio and 1 to alpha, and the larger of that ratio and 1 to -1.200.
3. Apply the age factor. Multiply by 0.9938 raised to the age in years.
4. Apply the female multiplier. For women, multiply the result by 1.012.

Creatinine in umol/L is divided by 88.4 to give mg/dL before the equation runs, as the NIDDK notes.

Take a 55-year-old woman with a serum creatinine of 0.9 mg/dL.

1. K = 0.7 and alpha = -0.241. Scr/K = 0.9 / 0.7 = 1.2857.
2. min(1.2857, 1) = 1, so the alpha term is 1 to the power of -0.241 = 1.
3. max(1.2857, 1) = 1.2857, so the high-creatinine term is 1.2857 to the power of -1.200 = 0.73966.
4. 0.9938 to the power of 55 = 0.71027. The female multiplier is 1.012.
5. eGFR = 142 x 1 x 0.73966 x 0.71027 x 1.012 = 75.5, shown as 75 mL/min/1.73 m2 (category G2).

A second worked case, a 60-year-old man with a creatinine of 1.2 mg/dL, gives 142 x 0.70808 x 0.68859 = 69.2, shown as 69 mL/min/1.73 m2 (category G2). Both cases are loaded as presets.

EGFR Stage Chart

G1 and G2 require a marker of kidney damage, such as albuminuria, to meet the definition of CKD. A normal eGFR on its own is not CKD.

The arithmetic is exact, but the creatinine number and the estimate itself depend on the person and the lab.

Creatinine and Muscle

Creatinine comes from muscle. A very muscular person can have a higher creatinine, and a person with low muscle a lower one, so the estimate can be too low or too high for them.

Age and Sex

The equation lowers the estimate with age through the 0.9938 age factor, and uses separate coefficients for women and men. The same creatinine gives different results across age and sex.

A Single Reading

One blood test is a snapshot. Creatinine shifts with hydration, diet and recent illness, so a single eGFR can move between tests.

Non-Standardised Creatinine

The equation expects standardised, IDMS-traceable creatinine. A lab method that is not standardised changes the result.

Creatinine-Only Estimate

This tool uses creatinine alone. The NIDDK notes the 2021 creatinine-cystatin C combined equation is considered more accurate, especially near decision thresholds.

In 2021 a National Kidney Foundation and American Society of Nephrology task force recommended a race-free equation. This calculator uses that current standard.

The older 2009 CKD-EPI and MDRD equations applied a separate factor for Black patients. The 2021 equation removes race and is the version shown on the NKF and NIDDK pages today.

Creatinine-Cystatin C

A separate 2021 equation combines creatinine with cystatin C and, per the NIDDK, is considered more accurate. It needs a cystatin C blood test, so it is not the default here.

To read more about what the number means, see our guide to eGFR and kidney function explained.

Reading a Lab Report

A blood panel often lists creatinine with an eGFR. This tool reproduces the CKD-EPI 2021 figure and shows the KDIGO category it falls in.

Converting Umol/L to Mg/dL

Reports outside the United States often give creatinine in umol/L. The tool converts by dividing by 88.4 before it calculates.

Checking a Calculation

The coefficient table and worked example let students and clinicians verify a spreadsheet or coursework answer against the published equation.

Alongside Other Measures

Kidney health sits with other numbers worth tracking, such as blood sugar in our HbA1c calculator and heart risk in our cardiovascular risk calculator.

1. Reading EGFR as a Diagnosis

A number is not a diagnosis. CKD is defined by a clinician using eGFR together with markers of kidney damage and repeat testing.

2. Treating a Normal Result as a Clean Bill

An eGFR of 90 or above can still occur with kidney damage. G1 and G2 need a damage marker such as albuminuria to count as CKD, and the damage can be present at any eGFR.

3. Acting on One Reading

Creatinine moves with hydration and illness. A low result needs a repeat test and a clinician before any conclusion.

4. Mixing Units

Entering a umol/L figure as mg/dL gives a wrong, very low result. Set the unit to match your report.

5. Using It for Children

This adult equation does not apply under 18. Children and teens use the separate CKiD U25 equation.

6. Changing Medicine Because of the Number

Treatment and dosing decisions belong with a clinician who sees your full history. Do not adjust anything based on this estimate.

The calculator reproduces the CKD-EPI 2021 creatinine equation and the KDIGO category cutoffs exactly. The limits lie in what one creatinine-based estimate can tell one person.

This is not a diagnosis. Discuss any result with a clinician, who can repeat the test and add clinical context.

An eGFR of 90 or above is category G1, normal or high, and 60 to 89 is G2, mildly decreased. On eGFR alone neither is CKD; a diagnosis of CKD also needs a marker of kidney damage.

An eGFR below 60 for at least three months, or any eGFR with a marker of kidney damage, can meet the definition. Only a clinician diagnoses CKD, using repeat testing and clinical context.

Yes. The CKD-EPI 2021 creatinine equation does not use race. A National Kidney Foundation and American Society of Nephrology task force recommended it, and the older race-based 2009 CKD-EPI and MDRD equations are deprecated.

Divide the umol/L value by 88.4. For example, 79.6 umol/L divided by 88.4 is about 0.9 mg/dL. The calculator does this for you when you pick umol/L.

No. This adult CKD-EPI 2021 equation applies to ages 18 and older. Children and teens use a separate pediatric equation, the CKiD U25.

Creatinine comes from muscle. A very muscular person may have a higher creatinine and a lower estimated eGFR, while a person with low muscle may have a higher one. The estimate can be off for them.

The NIDDK notes the 2021 creatinine-cystatin C combined equation is considered more accurate, especially near decision thresholds. It needs a cystatin C blood test, so this creatinine-only tool does not use it.

Not on its own. Kidney damage such as albuminuria can be present with a normal eGFR. A normal result still needs clinical interpretation alongside other tests.

No. This is an educational estimate, not medical advice. Do not start, stop or change any medicine because of it. Discuss results with a clinician.

No. The math runs in your browser. The Save button keeps results only in your own browser storage.

• CKD-EPI creatinine equation (2021): coefficients and formula (National Kidney Foundation; accessed 2026-10-04).
• eGFR equations for adults (CKD-EPI 2021) (NIDDK; accessed 2026-10-04).
• Estimated glomerular filtration rate (eGFR) and GFR categories (National Kidney Foundation; G1 to G5 cutoffs, accessed 2026-10-04).
• Recommendations for implementing the CKD-EPI 2021 race-free eGFR (National Kidney Foundation and ASN task force; accessed 2026-10-04).