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eGFR Calculator: CKD-EPI 2021 Creatinine Equation

By the Diabetes Blogs editorial teamLast reviewed

Sources: NKF; NKF/ASN; National Kidney Foundation; ADA Standards of Care in Diabetes—2026 (full list)

eGFR = 142 × min(Scr/κ, 1)α × max(Scr/κ, 1)−1.200 × 0.9938age × 1.012 [if female]. A 40-year-old man with a creatinine of 1.0 mg/dL gets an eGFR of about 98. Enter your numbers below for your eGFR and KDIGO category.

Calculate

Information only. Not for acute illness, pregnancy or anyone under 18. Nothing you type leaves your browser.

How it works

  1. Enter age, sex and creatinine. Use the number from your lab report. If it is in µmol/L, choose that unit; we divide by 88.4 to get mg/dL.
  2. We apply the published equation. κ is 0.7 for females and 0.9 for males; α is −0.241 for females and −0.302 for males.
  3. You see the category. The KDIGO table shows where the number falls. Share it with your care team.

Formula source: Inker LA et al., N Engl J Med 2021;385:1737, as published by the National Kidney Foundation. Scr is standardized serum creatinine in mg/dL.
We checked the code against the eight check values the NKF and ASN publish for laboratories (for example, a 90-year-old woman with creatinine 1.50 mg/dL gives 33).

Worked example

A 65-year-old man with a creatinine of 1.4 mg/dL: Scr/κ = 1.4 ÷ 0.9 = 1.56, so only the max term applies: 142 × 1.56−1.200 × 0.993865 = about 56, category G3a in the table below.

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KDIGO GFR categories

CategoryeGFR (mL/min/1.73 m²)Meaning
G190 or higherNormal or high
G260 to 89Mildly decreased
G3a45 to 59Mildly to moderately decreased
G3b30 to 44Moderately to severely decreased
G415 to 29Severely decreased
G5below 15Kidney failure range

Cut-offs as shown by the National Kidney Foundation. The NKF notes eGFR can be less accurate in the early categories, G1 and G2.

Yearly kidney checks with diabetes

The ADA 2026 Standards of Care (Section 11) say to check kidney function with a urine albumin-to-creatinine ratio (UACR) and an eGFR at least once a year in all people with type 2 diabetes and in people with type 1 diabetes of five or more years. Ask when yours are due. Kidney checks pair with blood pressure and your A1C.

What this calculator cannot do

  • It is for adults 18 and older. It is not valid in pregnancy or during acute illness.
  • It uses creatinine only. Your lab or clinician may also use cystatin C.
  • Muscle mass, diet and some medicines affect creatinine, so ask your clinician about unusual results.

Frequently asked questions

What is eGFR?

Estimated glomerular filtration rate. It estimates how well the kidneys filter blood, from your blood creatinine, age and sex. It is reported in mL/min/1.73 m². Labs usually report it with a creatinine test.

Which equation does this use?

The 2021 CKD-EPI creatinine equation, which does not use race. The ADA Standards of Care say this equation should be used to estimate GFR. The National Kidney Foundation publishes the formula.

How often should people with diabetes have their kidneys checked?

The ADA 2026 Standards say to assess urine albumin-to-creatinine ratio (UACR) and eGFR at least annually in people with type 1 diabetes of 5 or more years’ duration and in all people with type 2 diabetes, regardless of treatment.

Can I use this during an illness or pregnancy?

No. Creatinine-based eGFR assumes a steady state. It is not valid during acute illness, such as dehydration or acute kidney injury, or in pregnancy, and it is for adults 18 and older only.

Does a low eGFR mean I have kidney disease?

Not by itself. Kidney disease is diagnosed from persistent results and other tests, such as urine albumin. Bring the result to your clinician rather than drawing a conclusion.

Information only, not medical advice. Your care team may set different targets for you, and only a lab test ordered by a clinician can diagnose diabetes or prediabetes. See our medical disclaimer.

Sources

Last reviewed: by the Diabetes Blogs editorial team. Information only, not medical advice.

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