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eGFR Calculator

Estimate kidney filtration (eGFR) from serum creatinine with the race-free CKD-EPI 2021 equation and see the GFR category.

By Nitin Raturi · Last reviewed

Your worksheet

How to use the eGFR Calculator

Estimate kidney filtration from a creatinine blood test.

  1. Enter the serum creatinine from your report and choose its unit.
  2. Enter your age and sex.
  3. Read the eGFR and its GFR category.

Good to know

  • Results can vary with diet, muscle mass and illness; one test does not diagnose kidney disease.
  • The address stores your figures for sharing; anyone with the link can read them.

Estimated GFR from serum creatinine, age and sex with the race-free CKD-EPI 2021 equation, and the matching GFR category.

Serum creatinine

The creatinine level from your blood test report.

How to fill it in

  • Enter 0.1 to 20 mg/dL, or 9 to 1,800 µmol/L.
  • Use a result from a standardised (IDMS-traceable) assay, as most labs now report.

Example

A man of 50 with 1.0 mg/dL has an eGFR of about 92.

Creatinine unit

The unit your report uses.

How to fill it in

  • Choose mg/dL or µmol/L; 1 mg/dL is 88.4 µmol/L.

Example

88.4 µmol/L gives the same 92 as 1.0 mg/dL.

Age

Your age in whole years.

How to fill it in

  • Enter 18 to 110. For children, a different equation is used.

Example

At 70 instead of 50, the default eGFR falls to 81. A woman of 60 with 1.4 mg/dL is at 43, category G3b.

Sex

The equation uses different constants for men and women.

How to fill it in

  • Choose the sex recorded with your test.

Example

A woman of 50 with 1.0 mg/dL has an eGFR of about 69.

Estimated GFR (CKD-EPI 2021)

92 mL/min/1.73 m²

An eGFR of 92 mL/min/1.73 m² falls in GFR category G1: normal or high.

eGFR
91.7 mL/min/1.73 m²
Creatinine used
1.00 mg/dL
GFR category
G1: Normal or high

Categories G1 and G2 count as chronic kidney disease only with signs of kidney damage, such as albumin in the urine, for 3 months or more.

This estimate is for information only. Discuss your results with a doctor.

Race-free CKD-EPI creatinine equation (2021) for adults, with an IDMS-standardised creatinine result and a steady kidney function.

ChangelogHow we test this calculatorEmbed this calculator

How this calculator works

  1. Step 1Creatinine1.0 mg/dLA waste product the kidneys filter from blood.
  2. Step 2Age and sex50, maleThey change how much creatinine is normal.
  3. Step 3eGFR92mL/min/1.73 m², CKD-EPI 2021.
  4. Step 4CategoryG1Normal or high

GFR, the glomerular filtration rate, is how much blood the kidneys filter each minute. Measuring it directly is slow, so labs estimate it from creatinine in the blood.

This calculator uses the CKD-EPI creatinine equation from 2021, which does not use race. The National Kidney Foundation and the American Society of Nephrology recommend it.

Worked example: a man of 50 with creatinine 1.0 mg/dL

Estimate eGFR
eGFR
142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × 1.012 if female
  • κ0.9 for men, 0.7 for women 0.9
  • α−0.302 for men, −0.241 for women −0.302
  1. Scr / κ1.0 / 0.91.11
  2. min part1^−0.3021
  3. max part1.11^−1.2000.88
  4. Age part0.9938^500.73
  5. eGFR92 mL/min/1.73 m²

The National Kidney Foundation’s own calculator shows the same result, 92. A woman of the same age and creatinine has an eGFR of about 69.

What the categories mean

  • Man 50, 1.0 mg/dL92 (G1)
  • Man 70, 1.0 mg/dL81 (G2)
  • Woman 60, 1.4 mg/dL43 (G3b)
  • Man 70, 2.5 mg/dL27 (G4)
eGFR for some example cases

G1 is 90 or more, G2 60 to 89, G3a 45 to 59, G3b 30 to 44, G4 15 to 29 and G5 under 15. G1 and G2 count as kidney disease only with other signs of damage.

Age matters

  • Age 5092Man, 1.0 mg/dL.
  • Age 7081Each year multiplies eGFR by 0.9938.

Reading the result and its limits

eGFR is an estimate: muscle mass, diet, some medicines and acute illness change creatinine without changing kidney function.

Kidney disease is diagnosed from results that persist for three months or more, often with a urine albumin test. Discuss any result with a doctor.

eGFR is one result from a blood test. Body size and protein intake are separate questions for your doctor.

Some medicine doses use body surface area, which the body surface area calculator estimates by four formulas. For daily protein guidance for healthy adults, see the protein intake calculator; kidney disease needs advice from your care team.

Common mistakes

  • Mistake: Mixing up mg/dL and µmol/L.

    Instead: Check the unit on your report; 1 mg/dL is 88.4 µmol/L.

  • Mistake: Reading one low result as kidney disease.

    Instead: A diagnosis needs results over 3 months and a doctor’s review.

  • Mistake: Using it for a child.

    Instead: Children need a paediatric equation.

Methodology and sources

Tests compare the formula with an independent piecewise evaluation and with the National Kidney Foundation’s own calculator.

The equation and the category ranges come from the National Kidney Foundation. Sources, the review date and the health disclaimer follow.

Read how we test our calculators, or browse more health calculators.

Frequently asked questions

What is a normal eGFR?

An eGFR of 90 or more is category G1 and 60 to 89 is G2. Below 60 for three months or more may be a sign of chronic kidney disease.

Which equation does this calculator use?

The CKD-EPI creatinine equation (2021), which does not use race. For a man of 50 with creatinine 1.0 mg/dL it gives about 92; for a woman, 69.

Can I enter creatinine in µmol/L?

Yes. Choose µmol/L; the calculator divides by 88.4 to convert to mg/dL before using the equation.

Does a low eGFR mean I have kidney disease?

Not on its own. A woman of 60 with 1.4 mg/dL is at 43 (G3b), but diagnosis needs results over 3 months and a doctor’s review.

Can I use it for children?

No. It is for adults aged 18 and over. Children need a paediatric equation.

Sources and methodology

The formulas are standard time-value-of-money results. We check every figure against golden values worked out independently, by closed form and by month-by-month simulation; see the methodology.

Written and maintained by Nitin Raturi, a software engineer (about the author). Last reviewed 4 Nov 2026; next review due by . Found an error? Tell us.

Changelog

  • : Initial release.

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