eGFR from serum creatinine (mg/dL or µmol/L), age and sex by the race-free CKD-EPI 2021 equation, with optional cystatin C and the KDIGO G1–G5 stage.
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For a man aged 50 with creatinine 1.00 mg/dL, the 2021 CKD-EPI equation gives an eGFR of 92 mL/min/1.73 m². That is KDIGO category G1: normal or high.
| GFR category | eGFR | A1 (ACR < 30 mg/g) | A2 (30–300) | A3 (> 300) |
|---|---|---|---|---|
| G1 (you) | ≥ 90 | Low | Moderate | High |
| G2 | 60–89 | Low | Moderate | High |
| G3a | 45–59 | Moderate | High | Very high |
| G3b | 30–44 | High | Very high | Very high |
| G4 | 15–29 | Very high | Very high | Very high |
| G5 | < 15 | Very high | Very high | Very high |
The ratio is 1 or more, so the min term equals 1 and the max term uses −1.200.
KDIGO 2024 asks for eGFR to be reported as a whole number in mL/min/1.73 m².
Creatinine eGFR reported as 92 → G1: normal or high. Bands: G1 ≥ 90, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29, G5 < 15.
Estimated glomerular filtration rate (eGFR) is the volume of blood plasma the kidneys filter each minute, scaled to a body surface area of 1.73 m². It is calculated from serum creatinine, age and sex with the 2021 CKD-EPI equation, which dropped the race coefficient of the 2009 version; the National Kidney Foundation and the American Society of Nephrology recommend it for adults in the US. With a cystatin C result the 2021 creatinine–cystatin C equation is also computed, and KDIGO 2024 grades the kidneys on that combined value when it is available.
Clinicians use eGFR to stage chronic kidney disease and to adjust drug doses. A 50-year-old man with a creatinine of 1.0 mg/dL (88 µmol/L) has an eGFR of 92, category G1. An eGFR below 60 for more than 3 months is chronic kidney disease, category G3a or worse.
The equations assume creatinine is stable. They read wrong in acute kidney injury, pregnancy, very high or low muscle mass, and after a meat-heavy meal or creatine supplements.
eGFR is calculated from a blood creatinine result, age and sex with the 2021 CKD-EPI equation, which US kidney societies recommend for adults. A 50-year-old man with creatinine 1.0 mg/dL: 142 × (1.0 ÷ 0.9)^−1.200 × 0.9938^50 = 92 mL/min/1.73 m², category G1, normal or high.
The National Kidney Foundation's published form is:
eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × 1.012 if female
Only one of the min and max terms differs from 1. When creatinine is below κ the min term carries α; when it is above κ the max term carries −1.200.
For a 60-year-old woman with creatinine 0.8 mg/dL:
The age term lowers eGFR by 0.62 % a year, so the same creatinine of 1.0 mg/dL gives a man 92 at age 50 and 81 at age 70.
If your report gives creatinine in µmol/L, divide by 88.4 first. A result of 177 µmol/L is 2.00 mg/dL.
KDIGO 2024 grades the reported whole number:
Each row below is an independently evaluated example. The reported value uses creatinine alone unless cystatin C is entered, when it uses the combined equation.
| Formula sex | Age | Creatinine | Cystatin C | Reported eGFR | G category |
|---|---|---|---|---|---|
| Male | 50 | 1.0 mg/dL | Not entered | 92 | G1 |
| Female | 60 | .8 mg/dL | Not entered | 84 | G2 |
| Male | 70 | 177 µmol/L | Not entered | 35 | G3b |
| Female | 45 | .6 mg/dL | .9 mg/L | 103 | G1 |
| Male | 65 | 1.32 mg/dL | Not entered | 60 | G2 |
| Male | 65 | 1.34 mg/dL | Not entered | 59 | G3a |
| Female | 75 | 1.25 mg/dL | Not entered | 45 | G3a |
| Female | 70 | 5 mg/dL | Not entered | 9 | G5 |
The two 65-year-old men sit on a reporting boundary. Creatinine 1.32 gives 59.858, reported as 60 (G2); 1.34 gives 58.788, reported as 59 (G3a).
The estimate moved by about 1, but the label changed. Treat a result near a boundary as near it, not as a step change in the kidneys.
Cystatin C is a second blood marker, reported in mg/L. With both markers, KDIGO 2024 takes the GFR category from the combined 2021 equation, which is closer to measured GFR than either marker alone.
For a 45-year-old woman with creatinine 0.6 mg/dL and cystatin C 0.9 mg/L, creatinine alone gives 113, cystatin C alone 89 and the combined equation 103. Averaging the two single-marker results gives 100.6 instead.
KDIGO notes that 25 to 30 % of people show a gap this large, 15 or more or 20 % or more. It can point to muscle mass, diet or illness affecting one marker.
NIDDK's adult equation guidance discusses the value and limits of the combined estimate.
The urine albumin-to-creatinine ratio (ACR) adds a second axis:
The paired thresholds treat 1 mg/mmol as 10 mg/g. The exact factor, through creatinine's molar mass of 113.12 g/mol, is 8.84, so use the thresholds in the unit your lab reports.
The KDIGO 2024 guideline combines the G and A categories into a risk heat map:
The 65-year-old man with an eGFR of 59 (G3a) and an ACR of 45 mg/g (A2) falls in the high-risk cell. The heat map ranks groups; it does not give a personal probability or time to kidney failure.
An eGFR below 60 that lasts more than 3 months meets the KDIGO definition of chronic kidney disease on its own. G1 and G2 count as kidney disease only with signs of kidney damage, such as albumin in the urine, lasting at least 3 months.
One reading is not a diagnosis. Repeat the test and read it with earlier results and a clinician, because a single value can be low for temporary reasons.
eGFR is scaled to a body surface area of 1.73 m², not your own filtration rate in mL/min. A person with a BSA of 2.1 m² filters about 21 % more in absolute terms; the BSA calculator gives your surface area.
Checked against: 142 × (1.0/0.9)^−1.200 × 0.9938^50 = 91.691 (NKF 2021 CKD-EPI creatinine equation); 1.0 × 88.4 = 88.40 µmol/L
Checked against: 142 × (0.8/0.7)^−1.200 × 0.9938^60 × 1.012 = 84.298
Checked against: 177 / 88.4 = 2.00226 mg/dL; 142 × (2.00226/0.9)^−1.200 × 0.9938^70 = 35.195
Checked against: eGFRcr = 142 × (0.6/0.7)^−0.241 × 0.9938^45 × 1.012 = 112.735; eGFRcr-cys = 135 × (0.6/0.7)^−0.219 × (0.9/0.8)^−0.778 × 0.9961^45 × 0.963 = 102.910; eGFRcys = 133 × (0.9/0.8)^−1.328 × 0.996^45 × 0.932 = 88.513
90 mL/min/1.73 m² or higher is KDIGO category G1, normal or high, and 60 to 89 is G2, mildly decreased. Neither counts as chronic kidney disease unless there is also kidney damage, such as albumin in the urine, lasting at least 3 months. The equation lowers eGFR by 0.62 % for each year of age, so the same creatinine of 1.0 mg/dL gives a man 92 at age 50 and 81 at age 70.
An eGFR below 60 mL/min/1.73 m² that lasts more than 3 months meets the KDIGO 2024 definition of chronic kidney disease on its own. KDIGO grades it G3a (45–59), G3b (30–44), G4 (15–29) and G5, kidney failure (below 15). A single low reading is not a diagnosis, because acute illness, dehydration or a recent large meat meal can lower eGFR temporarily; KDIGO asks for repeat testing to confirm.
The 2009 CKD-EPI equation multiplied eGFR by 1.159 for Black patients, a coefficient based on race as a social category. A joint National Kidney Foundation and American Society of Nephrology task force recommended in 2021 that US labs switch to the refitted 2021 equation, which uses creatinine, age and sex only. KDIGO 2024 practice point 1.2.4.2 says race should not be used to compute eGFR.
When creatinine is likely to mislead. KDIGO 2024 Table 8 lists eating disorders, bodybuilding, above-knee amputation, spinal cord injury, vegetarian or high-protein diets and creatine supplements, among others. KDIGO recommends that when cystatin C is available the GFR category be taken from the combined creatinine–cystatin C equation, which is closer to measured GFR than either marker alone. A large gap between eGFRcr and eGFRcys is itself a signal that one of them is off.
Divide by 88.4, the factor in the KDIGO 2024 conversion table; it is 10,000 divided by the molar mass of creatinine, 113.12 g/mol. A result of 88 µmol/L is 1.00 mg/dL and 150 µmol/L is 1.70 mg/dL. KDIGO asks labs to report creatinine to the nearest whole number in µmol/L and to two decimals in mg/dL.
For information only, not medical advice. These formulas describe populations, not you; talk to a clinician before acting on a result.
This calculator includes 8 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.