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eGFR Calculator

years
mg/dL
mg/L

Your Results

For a 55-year-old woman with a creatinine of 0.9 mg/dL (80 µmol/L), the estimated GFR is 75 mL/min/1.73 m², stage G2 (mildly decreased). On its own this isn't kidney disease; G1 and G2 only count if there are other signs of kidney damage, such as protein in the urine. The average for healthy people around your age is about 93. It's an estimate from a blood test, and muscle mass, diet and some medicines can move creatinine.

75
eGFR (mL/min/1.73 m²)
G2
Kidney Function Stage
93
Typical at Your Age
80
Creatinine in µmol/L
Creatinine
Equation

Where your eGFR falls among the CKD stages

  • G5: under 15
  • G4: 15 to 29
  • G3b: 30 to 44
  • G3a: 45 to 59
  • G2: 60 to 89
  • G1: 90+
eGFR by Creatinine
Creatinine (mg/dL)eGFRStage
0.6106G1: Normal or high
0.887G2: Mildly decreased
0.975G2: Mildly decreased
1.067G2: Mildly decreased
1.253G3a: Mildly to moderately decreased
1.541G3b: Moderately to severely decreased
2.029G4: Severely decreased
2.522G4: Severely decreased
3.018G4: Severely decreased
4.013G5: Kidney failure
6.08G5: Kidney failure

For a 55-year-old woman, by the CKD-EPI 2021 creatinine equation. Higher creatinine means lower kidney function. Yours is highlighted.

What Is the Glomerular Filtration Rate?

The glomerular filtration rate, or GFR, is how much blood your kidneys filter each minute. It's the best single measure of kidney function. Measuring it directly is slow, so labs estimate it (eGFR) from a creatinine blood test, your age and your sex. Creatinine is a waste product from muscles that healthy kidneys clear, so when it builds up in the blood, the eGFR goes down. Doctors use it to find and stage chronic kidney disease (CKD).

CKD stages

eGFR is grouped into stages G1 to G5 (KDIGO), in mL/min/1.73 m²:

StageeGFRKidney Function
G190 or moreNormal or high
G260 to 89Mildly decreased
G3a45 to 59Mildly to moderately decreased
G3b30 to 44Moderately to severely decreased
G415 to 29Severely decreased
G5Under 15Kidney failure
  • When it's CKD: an eGFR under 60 for 3 months or more, or signs of kidney damage (such as protein in the urine) at any eGFR. A full CKD stage also uses a urine albumin test, which this calculator doesn't include.
  • Age: eGFR falls slowly with age, so a value in the 70s or 80s can be normal for an older adult.
  • Cystatin C: a second blood marker that doesn't depend on muscle, so combining it with creatinine gives a better estimate.

Which calculator should I use?

  • eGFR Calculator: to estimate kidney function and the CKD stage from a creatinine test.
  • HOMA-IR Calculator: to estimate insulin resistance from fasting glucose and insulin.
  • Glucose to A1C Calculator: to estimate A1C from your average blood sugar.

How to Calculate eGFR

The 2021 CKD-EPI creatinine equation, now used by most US labs, has no race term:

eGFR=142× min(Scrκ,1)α × max(Scrκ,1)−1.2 ×0.9938age×F
eGFR=142× min(Scrκ,1)α × max(Scrκ,1)−1.2 ×0.9938age×F
  • Scr: serum creatinine in mg/dL. From µmol/L, divide by 88.4.
  • κ: 0.7 for women, 0.9 for men.
  • α: −0.241 for women, −0.302 for men.
  • min and max: only one of them is used. If Scr ÷ κ is under 1 the min part applies, otherwise the max part.
  • F: 1.012 for women, 1 for men.

With cystatin C, the combined 2021 equation uses both markers and similar terms; the calculator switches to it when you enter cystatin C.

Example

A 55-year-old woman with a creatinine of 0.9 mg/dL:

  • Scr ÷ κ = 0.9 ÷ 0.7 = 1.286, more than 1, so the max part applies: 1.286−1.2 = 0.7397
  • Age: 0.993855 = 0.7103
  • eGFR: 142 × 0.7397 × 0.7103 × 1.012 = 75, stage G2 (mildly decreased).
  • A man of the same age and creatinine would have an eGFR of 101. With a cystatin C of 1.0 mg/L, the woman's combined estimate is 77.

Average eGFR in healthy adults by age:

AgeAverage eGFR
20 to 29116
30 to 39107
40 to 4999
50 to 5993
60 to 6985
70 and over75

How to Use the eGFR Calculator

"I'm a 55-year-old woman and my creatinine came back at 0.9 mg/dL. What does that say about my kidneys?" This calculator answers that.

Let's enter the numbers for this example in each box. They are already filled in when the calculator opens, so you can follow along and then change any box to match your own lab report.

  • Sex: Choose Female. The equation differs by sex because creatinine depends partly on muscle mass.
  • Age: Enter 55. The equation is for adults, so a whole number from 18 to 110.
  • Creatinine Unit: Choose mg/dL (US). µmol/L is used in many other countries. Switching converts the number you've typed.
  • Serum Creatinine: Enter 0.9, from your blood test. From 0.2 to 20 mg/dL, or 18 to 1,768 µmol/L.
  • Cystatin C: Leave it empty. If you have a cystatin C result, enter it in mg/L, from 0.2 to 10.

Calculate and Reset

Click Calculate to see your results. If a box has a problem, such as an age under 18, a message pops up under that box instead. With the default numbers you get:

  • Your Results: a short summary in words: an eGFR of 75, stage G2, what that stage means, and the average for your age.
  • eGFR: the headline, 75 mL/min/1.73 m².
  • Kidney Function Stage: G2, from the table above.
  • Typical at Your Age: about 93 for healthy people in their 50s.
  • Creatinine in µmol/L: 80, your result in the other unit. With cystatin C, this shows the creatinine-only eGFR instead.
  • Equation: which CKD-EPI 2021 equation was used.
  • Where your eGFR falls: a bar split into stages G5 to G1, with a marker at yours.
  • eGFR by Creatinine: the eGFR at your age and sex for creatinine from 0.6 to 6 mg/dL, with yours highlighted.
  • Share Results: a link that opens this calculator with your numbers filled in. Copy it, or share it on Facebook or X.

Click Reset to put every box back to its default. eGFR is less reliable during pregnancy, sudden illness, very high or low muscle mass, or with some medicines, and isn't for children. This is for information only, not medical advice: talk to your doctor about your kidney health.