eGFR Calculator
Kidney function from serum creatinine with the race-free CKD-EPI 2021 equation
An eGFR calculator estimates how much blood your kidneys filter each minute from a serum creatinine result, your age and your sex. With the race-free CKD-EPI 2021 equation that US laboratories use, a 58-year-old woman with a creatinine of 1.0 mg/dL has an eGFR of 65 mL/min/1.73 m², category G2 (mildly decreased). An eGFR below 60 that lasts at least 3 months meets the KDIGO definition of chronic kidney disease.
Last updated October 2026
Method: 2021 CKD-EPI creatinine equation (Inker et al., NEJM 2021) with the coefficients published by NIDDK; optional 2012 CKD-EPI cystatin C and 2021 creatinine-cystatin C equations; Cockcroft-Gault creatinine clearance (1976); Mosteller body surface area for an eGFR in mL/min; GFR categories from the KDIGO 2024 guideline. Creatinine in µmol/L is divided by 88.4 to get mg/dL.
Included: eGFR and its G category, creatinine in both units, cystatin C equations, creatinine clearance, body-size-adjusted eGFR, a step-by-step calculation and the creatinine levels at which eGFR crosses 60, 45, 30 and 15.
Not included: Equations for children, albuminuria staging, acute kidney injury, pregnancy, dialysis, measured GFR and drug-specific dose recommendations. Educational estimate, not a diagnosis.
🩸 Lab result and patient details
US labs report mg/dL. 1 mg/dL = 88.4 µmol/L.
Sex
Body size (for creatinine clearance)
Weight gives the Cockcroft-Gault creatinine clearance; weight plus height gives body surface area and an eGFR in mL/min for drug dosing. Leave blank if you only need the eGFR.
🩸 eGFR, CKD-EPI 2021 creatinine equation
One result does not diagnose chronic kidney disease: KDIGO requires abnormal kidney function or damage for at least 3 months, and categories G1 and G2 count as CKD only with other signs of kidney damage.
📊 Where this eGFR falls (KDIGO GFR categories)
Values in mL/min/1.73 m². Staging uses the whole-number eGFR, the way laboratories report it.
📋 Step-by-step
- 1. Constants for women. κ = 0.7, α = -0.241, female factor 1.012.
- 2. Creatinine ratio. 1.00 ÷ 0.7 = 1.4286 (above 1, so the steep −1.200 exponent applies).
- 3. Creatinine terms. min term 1.0000 × max term 0.6518.
- 4. Age factor. 0.9938^58 = 0.6972.
- 5. Multiply. 142 × 1.0000 × 0.6518 × 0.6972 × 1.012 = 65.30, reported as 65 mL/min/1.73 m².
- 6. Cockcroft-Gault. (140 − 58) × 69.85 kg × 0.85 ÷ (72 × 1.00) = 67.62 mL/min; body surface area 1.78 m².
🎯 Creatinine levels that cross each threshold
For a woman aged 58, the 2021 equation crosses these eGFR values at:
eGFR calculator: the CKD-EPI 2021 equation, stages and creatinine clearance
The glomerular filtration rate (GFR) is the volume of blood the kidneys' filtering units clear each minute, and it is the best single measure of kidney function. Measuring it directly requires timed clearance of an injected marker such as iohexol or iothalamate, which few clinics do routinely. An estimated GFR instead combines a blood test, usually creatinine, with age and sex, and reports the result per 1.73 m² of body surface area so that people of different sizes can be compared.
Two sister tools share this page's audience. The CHA2DS2-VASc Calculator scores stroke risk in atrial fibrillation, where kidney function guides anticoagulant dosing, and the QTc Calculator checks the QT interval during treatment with drugs such as sotalol and dofetilide, which the kidneys clear.
The CKD-EPI 2021 creatinine equation
eGFR = 142 × min(Scr/κ, 1)α × max(Scr/κ, 1)−1.200 × 0.9938age × 1.012 [if female] Scr is serum creatinine in mg/dL, and the min and max terms split the curve at the constant κ. Below κ the gentle exponent α applies; above it the steep exponent −1.200 takes over, which is why eGFR falls quickly once creatinine rises past about 0.7 mg/dL in women and 0.9 mg/dL in men.
| Constant | Women | Men |
|---|---|---|
| κ (creatinine knot) | 0.7 | 0.9 |
| α (exponent below κ) | −0.241 | −0.302 |
| Sex factor | 1.012 | 1 |
Why the equation no longer uses race
The earlier 2009 version multiplied eGFR by 1.159 for Black patients. In 2021 a task force of the National Kidney Foundation and the American Society of Nephrology recommended that all US laboratories move immediately to the CKD-EPI creatinine equation refit without race, and that cystatin C be used more routinely to confirm eGFR. NIDDK supports the race-free equations, and KDIGO's 2024 guideline says race should not be used in computing eGFR. In the validation data of 4,050 people, the race-free equation underestimated measured GFR in Black participants by a median of 3.6 and overestimated it in non-Black participants by 3.9 mL/min/1.73 m²; the combined creatinine-cystatin C equation was more accurate and narrowed that gap.
Worked example: a 58-year-old woman, creatinine 1.0 mg/dL
- Creatinine ratio: 1.0 ÷ 0.7 = 1.4286, above 1, so the min term is 1
- Max term: 1.4286−1.200 = 0.6518
- Age term: 0.993858 = 0.6972
- Product: 142 × 0.6518 × 0.6972 × 1.012 = 65.3
Reported as a whole number, her eGFR is 65 mL/min/1.73 m², category G2. Without signs of kidney damage such as albumin in the urine, G2 alone does not meet the definition of chronic kidney disease. These are the calculator's default inputs.
Second example: a 72-year-old man, creatinine 1.7 mg/dL
His ratio is 1.7 ÷ 0.9 = 1.8889, the max term 1.8889−1.200 = 0.4662 and the age term 0.993872 = 0.6390. The product 142 × 0.4662 × 0.6390 = 42.3 gives an eGFR of 42, category G3b. If that level persists for 3 months it is chronic kidney disease, moderately to severely decreased. The same steps work for results in µmol/L after dividing by 88.4: a 45-year-old man with 97 µmol/L has 1.0973 mg/dL and an eGFR of 85, category G2.
eGFR by creatinine, age and sex
Computed with the calculator's equation; creatinine in mg/dL with µmol/L in brackets, eGFR in mL/min/1.73 m² with the KDIGO category.
| Creatinine | Man 40 | Woman 40 | Man 60 | Woman 60 | Man 80 | Woman 80 |
|---|---|---|---|---|---|---|
| 0.6 (53) | 125 G1 | 116 G1 | 111 G1 | 103 G1 | 98 G1 | 91 G1 |
| 0.8 (71) | 115 G1 | 95 G1 | 101 G1 | 84 G2 | 89 G2 | 74 G2 |
| 1.0 (88) | 98 G1 | 73 G2 | 86 G2 | 64 G2 | 76 G2 | 57 G3a |
| 1.2 (106) | 78 G2 | 59 G3a | 69 G2 | 52 G3a | 61 G2 | 46 G3a |
| 1.5 (133) | 60 G2 | 45 G3a | 53 G3a | 40 G3b | 47 G3a | 35 G3b |
| 2.0 (177) | 42 G3b | 32 G3b | 38 G3b | 28 G4 | 33 G3b | 25 G4 |
| 2.5 (221) | 32 G3b | 24 G4 | 29 G4 | 21 G4 | 25 G4 | 19 G4 |
| 3.0 (265) | 26 G4 | 20 G4 | 23 G4 | 17 G4 | 20 G4 | 15 G4 |
| 4.0 (354) | 18 G4 | 14 G5 | 16 G4 | 12 G5 | 14 G5 | 11 G5 |
| 5.0 (442) | 14 G5 | 11 G5 | 12 G5 | 9 G5 | 11 G5 | 8 G5 |
The same creatinine of 1.0 mg/dL means G1 for a 40-year-old man but G3a for an 80-year-old woman, which is why a creatinine value on its own is a poor guide to kidney function.
Creatinine levels at which eGFR crosses each threshold
Solving the equation backward gives the creatinine (mg/dL) at which eGFR reaches 60, 45, 30 and 15:
| eGFR | Man 40 | Woman 40 | Man 60 | Woman 60 | Man 80 | Woman 80 |
|---|---|---|---|---|---|---|
| 60 | 1.50 | 1.18 | 1.35 | 1.06 | 1.22 | 0.96 |
| 45 | 1.91 | 1.50 | 1.72 | 1.35 | 1.55 | 1.22 |
| 30 | 2.67 | 2.10 | 2.41 | 1.89 | 2.17 | 1.71 |
| 15 | 4.76 | 3.74 | 4.29 | 3.37 | 3.87 | 3.04 |
An 80-year-old woman reaches an eGFR of 60 at a creatinine of 0.96 mg/dL, while a 40-year-old man does not reach it until 1.50 mg/dL. The calculator shows these four cut points for whatever age and sex you enter.
CKD stages G1 to G5
| Category | GFR (mL/min/1.73 m²) | KDIGO term |
|---|---|---|
| G1 | 90 or above | Normal or high |
| G2 | 60 to 89 | Mildly decreased |
| G3a | 45 to 59 | Mildly to moderately decreased |
| G3b | 30 to 44 | Moderately to severely decreased |
| G4 | 15 to 29 | Severely decreased |
| G5 | below 15 | Kidney failure |
KDIGO defines chronic kidney disease as abnormal kidney structure or function lasting at least 3 months: a GFR below 60, or a marker of damage such as a urine albumin-to-creatinine ratio of 30 mg/g or more. Staging combines the G category with the albuminuria category (A1 below 30, A2 30 to 300, A3 above 300 mg/g), so a person whose eGFR of 75 and albumin ratio of 150 mg/g persist for 3 months has CKD G2 A2.
Adding cystatin C
Cystatin C is a second filtration marker that depends far less on muscle mass. KDIGO recommends the combined creatinine-cystatin C equation when the creatinine estimate is likely to be less accurate and the result affects decisions. Two examples show why it can move the answer in either direction:
- A 70-year-old woman with a creatinine of 1.2 mg/dL has a creatinine eGFR of 49 (G3a). With a cystatin C of 1.0 mg/L, the cystatin C equation gives 70 and the combined equation 62 (G2).
- A frail 82-year-old woman with a creatinine of 0.7 mg/dL has a creatinine eGFR of 86 (G2). With a cystatin C of 1.5 mg/L, the cystatin C equation gives 39 and the combined equation 58 (G3a). Low muscle mass had made her creatinine look healthier than her kidneys.
Creatinine clearance (Cockcroft-Gault) and drug dosing
CrCl (mL/min) = (140 − age) × weight (kg) ÷ (72 × Scr) × 0.85 [if female] eGFR (mL/min) = eGFR (mL/min/1.73 m²) × BSA ÷ 1.73 Cockcroft and Gault derived their formula in 1976 from 249 patients aged 18 to 92, and many drug labels still state kidney cutoffs in its terms. For a 70-year-old woman weighing 154 lb (69.85 kg) with a creatinine of 1.2 mg/dL: (140 − 70) × 69.85 × 0.85 ÷ 86.4 = 48 mL/min. At 5 ft 4 in her Mosteller body surface area is 1.78 m², so her eGFR of 48.7 becomes 48.7 × 1.776 ÷ 1.73 = 50 mL/min without indexing. FDA guidance from 2024 says an eGFR used for dosing should be expressed this way, in mL/min, and notes that ideal or adjusted body weight is likely to give a more accurate Cockcroft-Gault result in people with overweight or obesity. NIDDK adds that the FDA does not favor one equation and that the combined cystatin C equation is worth considering when a result sits near a dosing cutoff.
How to use this calculator
Enter the creatinine from your lab report and pick the unit, then age and sex. The headline shows the eGFR and its category. Tick the cystatin C box if you have that result. Weight unlocks the Cockcroft-Gault clearance, and weight plus height adds body surface area and an eGFR in mL/min; leave them blank if you only need the eGFR. The step-by-step card shows every intermediate number.
Who this calculator is for
It serves patients reading a metabolic panel, people with diabetes or high blood pressure who track kidney function, pharmacy and medical students learning the equations, and clinicians who want the creatinine, cystatin C and Cockcroft-Gault numbers side by side.
Key terms
- GFR: glomerular filtration rate, the volume of blood filtered by the kidneys per minute.
- Creatinine: a waste product of muscle that the kidneys filter; it rises as filtration falls.
- Cystatin C: a small protein filtered by the kidneys, used as a second filtration marker that depends less on muscle mass.
- mL/min/1.73 m²: filtration scaled to a standard adult body surface area so people of different sizes can be compared.
- Albuminuria: albumin in the urine, measured as the albumin-to-creatinine ratio, a marker of kidney damage.
What changes eGFR
NIDDK lists the situations in which creatinine-based eGFR is less accurate: unstable creatinine during pregnancy, serious illness or acute kidney injury; extremes of body size, muscle mass or diet, such as amputation, paraplegia, bodybuilding, frailty, malnutrition or a vegetarian diet; critical illness; cancer; muscle-wasting disorders; and some drugs. Cystatin C is affected by steroid use, thyroid dysfunction, adiposity and inflammation. Age alone lowers the estimate by about 0.6% per year at the same creatinine, from the 0.9938 age term.
Limitations
Every equation estimates an average relationship, and NIDDK notes that imprecision is inherent in all of them; in the 2021 validation data, at least 85% of estimates were within 30% of measured GFR, so some were further off. eGFR is not valid for children, during pregnancy or when kidney function is changing quickly, and it does not replace urine albumin testing or a clinician's assessment.
Related calculators
- Body surface area on its own: BSA Calculator.
- Ideal body weight for Cockcroft-Gault in people with obesity: Ideal Weight Calculator.
- Body size and composition: BMI Calculator and Lean Body Mass Calculator.
- Heart checks that often accompany kidney tests: CHA2DS2-VASc Calculator and QTc Calculator.
Sources
- Inker LA, Eneanya ND, Coresh J, et al. (2021). New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. New England Journal of Medicine 385:1737-1749. PubMed
- Inker LA, Schmid CH, Tighiouart H, et al. (2012). Estimating Glomerular Filtration Rate from Serum Creatinine and Cystatin C. New England Journal of Medicine 367:20-29. PubMed
- Delgado C, Baweja M, Crews DC, et al. (2021). A Unifying Approach for GFR Estimation: Recommendations of the NKF-ASN Task Force. Journal of the American Society of Nephrology 32:2994-3015. PubMed
- KDIGO CKD Work Group (2024). KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney International 105(4S):S117-S314. PubMed
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): eGFR equations for adults, clinical measurements and eGFR accuracy, drug dosing in CKD and CKD tests and diagnosis.
- U.S. Food and Drug Administration (2024). Pharmacokinetics in Patients with Impaired Renal Function: Study Design, Data Analysis, and Impact on Dosing. fda.gov
- Cockcroft DW, Gault MH (1976). Prediction of creatinine clearance from serum creatinine. Nephron 16:31-41. PubMed. Mosteller RD (1987). Simplified calculation of body-surface area. New England Journal of Medicine 317:1098. PubMed
⚠️ Common mistakes & edge cases
Entering µmol/L as mg/dL
A creatinine of 88 means 88 µmol/L (1.0 mg/dL), not 88 mg/dL. Mixing the units produces an eGFR near zero, so the calculator refuses creatinine values above 20 mg/dL and asks for the right unit.
Diagnosing CKD from one test
CKD requires abnormal results for at least 3 months. A single low eGFR, for example after an unusual meal or during an illness, should be repeated before anyone draws conclusions.
Comparing old and new lab reports directly
Reports issued before laboratories switched to the 2021 equation used the 2009 formula with a race term, so part of a change between an older and a newer report can come from the equation rather than the kidneys.
Dosing from the indexed eGFR in a very large or small person
The value per 1.73 m² is for staging. For dosing, FDA guidance converts it to mL/min with the person's own body surface area, which the calculator does when you enter height and weight.
Using actual weight in Cockcroft-Gault with obesity
Actual weight inflates creatinine clearance in people with obesity. FDA guidance notes that ideal or adjusted body weight is likely more accurate; enter that weight instead when it applies.
Ignoring muscle mass
Bodybuilders can look like they have kidney disease and frail older adults can look healthy, because creatinine tracks muscle. That is the situation in which cystatin C helps most.
❓ Frequently asked questions
What is a normal eGFR?
NIDDK describes an eGFR of 60 or higher as in the normal range and a value below 60 as a possible sign of kidney disease. On the KDIGO scale, 90 or above is category G1 and 60 to 89 is G2, mildly decreased compared with young adult levels. The equation itself lowers the estimate by about 0.6% for each year of age at the same creatinine, so healthy older adults often score lower than young ones.
What eGFR means chronic kidney disease?
KDIGO defines chronic kidney disease as a GFR below 60 mL/min/1.73 m² or other signs of kidney damage, such as a urine albumin-to-creatinine ratio of 30 mg/g or more, lasting at least 3 months. The stages below 60 are G3a (45 to 59), G3b (30 to 44), G4 (15 to 29) and G5 (below 15, kidney failure). An eGFR of 60 or more counts as CKD only when another marker of damage is present.
What eGFR is stage 3 kidney disease?
KDIGO splits stage 3 into G3a, an eGFR of 45 to 59 (mildly to moderately decreased), and G3b, 30 to 44 (moderately to severely decreased). Either one counts as chronic kidney disease only when it lasts at least 3 months. For a 60-year-old woman, the 2021 equation crosses 60 at a creatinine of about 1.06 mg/dL and 45 at about 1.35 mg/dL, so a creatinine in that range points to G3a.
How is eGFR calculated from creatinine?
The CKD-EPI 2021 equation multiplies 142 by two creatinine terms, an age term and, for women, a factor of 1.012. For a 58-year-old woman with a creatinine of 1.0 mg/dL, creatinine divided by 0.7 is 1.4286, which raised to the power -1.200 gives 0.6518; the age term 0.9938^58 is 0.6972. The product 142 × 0.6518 × 0.6972 × 1.012 is 65.3, reported as 65 mL/min/1.73 m².
Why was race removed from the eGFR equation?
The 2009 equation multiplied eGFR by 1.159 for Black patients, so the same creatinine produced a higher estimate. A task force of the National Kidney Foundation and the American Society of Nephrology recommended in 2021 that all US laboratories switch to the CKD-EPI creatinine equation refit without race, and KDIGO advises avoiding race in eGFR. In its validation data, the new equation was within 30% of measured GFR in at least 85% of both Black and non-Black participants.
What is the difference between eGFR and creatinine clearance?
eGFR from CKD-EPI estimates filtration scaled to a standard body surface area of 1.73 m² and does not need body weight. Creatinine clearance from the Cockcroft-Gault formula, published in 1976, uses weight and is expressed in mL/min. Many drug labels state kidney cutoffs as Cockcroft-Gault clearance. FDA guidance from 2024 accepts either estimate for dosing and says an eGFR used for dosing should be converted to mL/min with the patient's own body surface area.
How do I convert creatinine from µmol/L to mg/dL?
Divide by 88.4. A creatinine of 106 µmol/L is 106 ÷ 88.4 = 1.20 mg/dL, and 1.0 mg/dL is 88.4 µmol/L. US laboratories report mg/dL; most other countries use µmol/L. The calculator converts automatically when you switch units, and it rejects values that look like the wrong unit, such as 88 entered as mg/dL.
When should cystatin C be tested?
KDIGO recommends adding cystatin C and using the combined creatinine-cystatin C equation when the creatinine-based eGFR is likely to be less accurate and the result affects clinical decisions. Typical reasons are very high or low muscle mass, amputation, frailty, unusual diets and results close to a treatment or dosing threshold. Cystatin C has its own pitfalls: steroid use, thyroid dysfunction, adiposity and inflammation can affect it.
Can the eGFR calculator be used for children, pregnancy or sudden kidney injury?
No. The CKD-EPI equations are for adults 18 and older; for children and young adults NIDDK lists the CKiD U25 equations. Every equation assumes a stable creatinine, so results are unreliable during pregnancy, acute kidney injury or a hospital stay in which creatinine is changing day to day.
Why did my eGFR change between two tests?
Creatinine depends on muscle mass and diet as well as the kidneys, and some medicines change it, so results vary from one test to the next. KDIGO advises considering dietary intake when interpreting creatinine. A single change is best confirmed with a repeat test, and a sustained drop is what matters for staging.
💡 Good to know
Doubling creatinine more than halves eGFR
Above the knot, eGFR scales with creatinine to the power −1.2, and 2−1.2 is 0.435. For a 60-year-old man, 1.0 mg/dL gives 86 and 2.0 mg/dL gives 38.
Normal range does not mean no disease
An eGFR of 60 or more can still be CKD when the urine shows albumin. That is why kidney screening pairs the blood test with a urine albumin-to-creatinine ratio.
Outside the US the unit may differ
Some reports give eGFR in mL/s/1.73 m². Divide mL/min/1.73 m² by 60 to convert, so 65 becomes about 1.08.