M+QuickMedCalc
Educational reference only. Not a diagnostic tool. See full disclaimer.
NephrologyeGFR

Adult eGFR Calculator

Estimate adult race-free indexed glomerular filtration rate (eGFR) with 2021 CKD-EPI creatinine or combined creatinine–cystatin C and the 2012 cystatin C equation.

Content updated: View sources

QuickMedCalc is developed and maintained by an independent developer. Medical content is not independently reviewed by a physician.

Formula and medical content are based on the references listed on this page. See sources, About, and Sources and Review Process.

Choose the adult CKD-EPI task by entering creatinine, cystatin C, or both. The calculator does not choose a biomarker or infer which estimate is individually most appropriate.

Adult CKD-EPI: age 18 or older. Ages 18–25 have additional equation considerations below.

The female/male coefficient is part of the published CKD-EPI equations; it is not an inference about gender identity.

Serum creatinine (optional)

Use an IDMS-traceable assay when available.

Changing the unit clears creatinine.

Enter mg/L from an IFCC-standardized assay when available.

Your eGFR result will appear here

Enter creatinine for the 2021 CKD-EPI eGFRcr, cystatin C for the 2012 eGFRcys, or both for the 2021 combined eGFRcr-cys plus the two paired single-marker estimates.

When both biomarkers are entered, confirm that they are paired in time before calculation.

About

This adult calculator implements three indexed GFR estimates: 2021 CKD-EPI creatinine (eGFRcr), 2012 CKD-EPI cystatin C (eGFRcys), and 2021 CKD-EPI creatinine–cystatin C (eGFRcr-cys). The 2021 equations are race-free; this page does not request race or calculate the historical 2009 race coefficient. [1, 13, 14]

Creatinine alone produces eGFRcr, cystatin C alone produces eGFRcys, and paired values produce all three estimates with eGFRcr-cys as the primary result. Paired confirmation is required only when both biomarkers are entered, so the combined result and comparison use the same specimen or a reasonably paired time point. [1, 7]

Every result is an estimate indexed to 1.73 m², not measured GFR. It does not by itself diagnose CKD or decide a medicine dose, referral, dialysis, or transplant assessment. [5, 10]

Formula

2021 CKD-EPI eGFRcr: 142 × min(SCr/κ,1)^α × max(SCr/κ,1)^−1.200 × 0.9938^age × 1.012 if female (female: κ 0.7, α −0.241; male: κ 0.9, α −0.302). [1, 6]
2012 CKD-EPI eGFRcys: 133 × min(Scys/0.8,1)^−0.499 × max(Scys/0.8,1)^−1.328 × 0.996^age × 0.932 if female. [2, 3, 6]
2021 CKD-EPI eGFRcr-cys: 135 × min(SCr/κ,1)^α × max(SCr/κ,1)^−0.544 × min(Scys/0.8,1)^−0.323 × max(Scys/0.8,1)^−0.778 × 0.9961^age × 0.963 if female (female: κ 0.7, α −0.219; male: κ 0.9, α −0.144). [1, 6]
SCr is creatinine in mg/dL; Scys is cystatin C in mg/L. [4, 6] Creatinine µmol/L ÷ 88.4 = mg/dL. [6] The 2009 race-adjusted equation is historical and is not calculated here. [1, 13]

Interpretation

G range
G1 numerical range
Displayed primary eGFR
≥90 mL/min/1.73 m²
G range
G2 numerical range
Displayed primary eGFR
60–89 mL/min/1.73 m²
G range
G3a numerical range
Displayed primary eGFR
45–59 mL/min/1.73 m²
G range
G3b numerical range
Displayed primary eGFR
30–44 mL/min/1.73 m²
G range
G4 numerical range
Displayed primary eGFR
15–29 mL/min/1.73 m²
G range
G5 numerical range
Displayed primary eGFR
<15 mL/min/1.73 m²

These are G numerical ranges, not stand-alone diagnoses. A single low eGFR cannot diagnose CKD. CKD requires abnormalities of kidney structure or function—including reduced GFR or markers of kidney damage—to be present for at least 3 months. G1 or G2 does not establish CKD without persistent evidence of kidney damage. Assessment also considers urine ACR/albuminuria, cause, trend, and clinical context. [5]

This calculator does not convert a G range into treatment, referral, dosing, dialysis, or transplant instructions.

How this eGFR calculator works

  • Creatinine only: 2021 CKD-EPI eGFRcr.
  • Cystatin C only: 2012 CKD-EPI eGFRcys.
  • Both paired markers: 2021 CKD-EPI eGFRcr-cys is primary, with eGFRcr and eGFRcys shown for paired comparison.

Serum creatinine may be entered in mg/dL or µmol/L; µmol/L is divided by 88.4. Cystatin C is entered in mg/L. The runtime keeps unrounded values through the equation, then reports the final eGFR as a whole number. [6, 7]

Creatinine, cystatin C, and the combined equation

Creatinine and cystatin C have different non-GFR determinants. When both are clinically available at a comparable time point, the 2021 combined equation is generally more accurate than either single-marker equation; the two single-marker values can still make the direction and magnitude of their difference visible. No difference shown here determines which marker is correct or why they differ. [1, 5, 7]

What an eGFR result means

The result estimates filtration indexed to a standard body surface area of 1.73 m². The displayed G range is numerical context, not a diagnosis, disease probability, or treatment recommendation. Kidney assessment also considers chronicity, albuminuria such as urine ACR, cause, serial trend, and the wider clinical context. [5, 14]

What is a normal eGFR for age?

The National Kidney Foundation provides the following descriptive average eGFR values by age. They describe populations; they are not individualized normal ranges or age-adjusted CKD thresholds. [15]

Age (years)
20–29
Descriptive average eGFR
116 mL/min/1.73 m²
Age (years)
30–39
Descriptive average eGFR
107 mL/min/1.73 m²
Age (years)
40–49
Descriptive average eGFR
99 mL/min/1.73 m²
Age (years)
50–59
Descriptive average eGFR
93 mL/min/1.73 m²
Age (years)
60–69
Descriptive average eGFR
85 mL/min/1.73 m²
Age (years)
70+
Descriptive average eGFR
75 mL/min/1.73 m²

An eGFR below an age-group average does not diagnose CKD. Diagnosis depends on chronicity, kidney-damage markers such as albuminuria, and clinical context; the KDIGO G thresholds are not automatically shifted by age.

Ages 18–25 need additional equation context

The adult CKD-EPI calculators apply from age 18. For ages 18–25, NIDDK recommends referring to both the adult calculator and the pediatric CKiD U25 calculator; comparison can provide a more informed assessment. This page calculates only adult CKD-EPI and does not implement CKiD U25. The U25 source population and clinical context remain important when interpreting that separate estimate. [8, 9]

eGFR versus creatinine clearance

CKD-EPI eGFR estimates GFR indexed to 1.73 m². Cockcroft–Gault is a different, weight-based estimate of creatinine clearance in mL/min. They are not interchangeable. The appropriate kidney-function measure depends on applicable labeling or protocol together with current institutional and clinical guidance; this calculator does not choose the measure, medicine, or dose. Use the separate Cockcroft–Gault Creatinine Clearance Calculator when that is the named task. [10, 11]

Indexed versus nonindexed eGFR

This page reports mL/min/1.73 m². A mathematical conversion sometimes used to remove BSA indexing is nonindexed eGFR = indexed eGFR × BSA ÷ 1.73, but this page does not collect BSA or perform that conversion. The separate Adult Anthropometry Workspace can calculate BSA without changing this eGFR result. [10]

Drug labels and protocols may specify different kidney-function measures. This calculator does not select a medicine, dose, referral pathway, dialysis decision, or transplant assessment.

When eGFR estimates may be less reliable

  • AKI or rapidly changing creatinine can violate the steady-state assumption.
  • Creatinine can be influenced by muscle mass, amputation, frailty, malnutrition, creatine supplements, diet, tubular secretion, and some medicines.
  • Cystatin C can have non-GFR associations with inflammation, smoking, obesity, thyroid status, glucocorticoids, cancer, high cell turnover, heart failure, and cirrhosis.
  • If both biomarkers have important non-GFR determinants, the combined estimate can also be inaccurate.
  • These adult equations are not valid for pregnancy. [12]

Higher estimates are generally less precise, and a same-equation trend can be more informative than one result. Accuracy-critical decisions may require measured GFR rather than another estimating equation. [5, 7, 10]

References

  1. Inker LA, et al. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. N Engl J Med. 2021;385(19):1737–1749. PMID 34554658. DOI 10.1056/NEJMoa2102953.
  2. Inker LA, et al. Estimating Glomerular Filtration Rate from Serum Creatinine and Cystatin C. N Engl J Med. 2012;367(1):20–29. PMID 22762315. DOI 10.1056/NEJMoa1114248.
  3. Inker LA, et al. Estimating Glomerular Filtration Rate from Serum Creatinine and Cystatin C. Formula correction. N Engl J Med. 2012;367:681. DOI 10.1056/NEJMx120052.
  4. Inker LA, et al. Estimating Glomerular Filtration Rate from Serum Creatinine and Cystatin C. Cystatin C unit correction. N Engl J Med. 2012;367:2060. DOI 10.1056/NEJMx120062.
  5. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease.
  6. NIDDK. eGFR Equations for Adults.
  7. NIDDK. Glomerular Filtration Rate Equations: equation selection, reporting, standardization, and limitations.
  8. NIDDK. eGFR Calculators for Adults & Pediatrics: age ranges and guidance for ages 18–25.
  9. NIDDK. eGFR Equations for Children, Adolescents, and Young Adults, including CKiD U25.
  10. NIDDK. Determining Drug Dosing in Adults with Chronic Kidney Disease.
  11. FDA. Pharmacokinetics in Patients with Impaired Renal Function — Study Design, Data Analysis, and Impact on Dosing. Guidance for Industry. March 2024.
  12. Wiles K, et al. Clinical practice guideline on pregnancy and renal disease. BMC Nephrol. 2019;20:401. PMID 31672135. DOI 10.1186/s12882-019-1560-2.
  13. Delgado C, et al. A Unifying Approach for GFR Estimation: Recommendations of the NKF-ASN Task Force. Am J Kidney Dis. 2022;79(2):268–288.e1. PMID 34563581. DOI 10.1053/j.ajkd.2021.08.003.
  14. National Kidney Foundation. CKD-EPI Creatinine-Cystatin Equation (2021) eGFR Calculator.
  15. National Kidney Foundation. Estimated Glomerular Filtration Rate (eGFR): descriptive average eGFR by age.

FAQ

Related Calculators

CrCl

Calculate adult creatinine clearance (CrCl) with the Cockcroft–Gault equation using age, an explicit weight basis, serum creatinine, and the published sex coefficient.

Anthropometry

Calculate adult body surface area (BSA) with an explicitly selected Mosteller, Du Bois, or Haycock formula and BMI from height and weight; add optional measurements for other named anthropometry models.

UPCR / PCR

Calculate spot urine total protein divided by same-specimen creatinine in mg/g, mg/mmol, and mg/mg, with interpretation boundaries distinct from ACR and measured 24-hour protein.

Disclaimer

Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.