Thursday, June 25, 2026
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Renal Function Calculator

GFR Calculator: CKD-EPI 2021 and MDRD eGFR

Estimate adult kidney function using the race-free CKD-EPI 2021 creatinine equation, compare against legacy MDRD, and optionally calculate BSA-adjusted absolute eGFR for medication-related decisions.

Quick Answer

Estimated glomerular filtration rate (eGFR) measures kidney filtration in mL/min/1.73 m² from serum creatinine, age, and sex. This calculator uses the race-free CKD-EPI 2021 equation recommended by NKF and KDIGO for adult kidney function reporting. Pharma professionals use eGFR for CKD staging, renal impairment cohorts in PK studies, oncology trial eligibility, contrast-risk assessment, and dose adjustment when drug labels reference kidney function categories.

CKD-EPI Creatinine Equation (2021)
eGFR = 142 × min(SCr / κ, 1)α × max(SCr / κ, 1)-1.200 × 0.9938Age × 1.012 [if female]
SCr = standardized serum creatinine in mg/dL; κ = 0.7 female, 0.9 male; α = -0.241 female, -0.302 male.

Calculate eGFR

Estimate kidney function with CKD-EPI 2021. Add height and weight for BSA-adjusted absolute eGFR in mL/min.

Patient inputs

CKD-EPI 2021 is intended for adults aged 18 and older.

Laboratory values

μmol/L values are converted to mg/dL by dividing by 88.4.

Optional anthropometrics

Enter both height and weight to calculate DuBois BSA and absolute eGFR in mL/min.

Primary eGFR

-

mL/min/1.73 m² by CKD-EPI 2021

CKD-EPI 2021
-
mL/min/1.73 m²
MDRD Reference
-
mL/min/1.73 m², no race coefficient
BSA-adjusted eGFR
-
mL/min
Body Surface Area
-
m², DuBois

How to Use the GFR Calculator

1
Enter adult age and sex. CKD-EPI 2021 is intended for adults and uses age and sex as model variables.
2
Enter serum creatinine and select the correct unit. μmol/L values are converted to mg/dL by dividing by 88.4.
3
Optionally enter height and weight to calculate DuBois BSA and absolute eGFR in mL/min for medication-related decisions.
4
Review CKD-EPI 2021 as the primary value, MDRD without race coefficient as a legacy comparator, and the GFR stage classification.

Worked Example

Example calculation

Patient: 65-year-old female, serum creatinine 1.2 mg/dL, height 165 cm, weight 70 kg.

CKD-EPI 2021: κ = 0.7, α = -0.241, female multiplier = 1.012.

Indexed eGFR: approximately 51 mL/min/1.73 m², consistent with G3a if persistent.

BSA-adjusted eGFR: if BSA is 1.77 m², absolute eGFR = 51 × 1.77 / 1.73 = approximately 52 mL/min.

CKD-EPI 2021 vs MDRD

CKD-EPI 2021 is the preferred creatinine-based adult eGFR equation because it removes the race coefficient from older equations and performs better than MDRD, particularly at higher GFR values. MDRD remains useful as a legacy comparator because older laboratory reports, publications, and clinical systems may still reference it.

This calculator reports CKD-EPI 2021 as the primary eGFR value and MDRD without the legacy race coefficient as a reference value. Both are estimates and should be interpreted with assay standardization, muscle mass, diet, acute illness, and medication context in mind.

Pharma & clinical trial context

Renal impairment is a core stratification variable in pharmacokinetic studies and registrational trials. Sponsors define renal function cohorts using eGFR, measured GFR, or Cockcroft-Gault CrCl depending on FDA/EMA guidance and the reference drug label. eGFR categories (G3a, G3b, G4) often map to dose-reduction tables in oncology, anti-infective, and immunology protocols.

Indexed eGFR (mL/min/1.73 m²) is standard for CKD staging and laboratory reporting. For medication decisions in patients with atypical body size, absolute BSA-adjusted eGFR in mL/min may better reflect drug clearance. Many labels still reference Cockcroft-Gault CrCl—use our Creatinine Clearance Calculator when the prescribing information or protocol requires CrCl rather than eGFR.

Renal and hepatic impairment are often assessed together in development programs. While eGFR addresses kidney function, hepatic impairment PK studies use Child-Pugh classification. For cirrhosis severity and hepatic dosing context, see our Child-Pugh Score Calculator.

Medication Dosing: Indexed vs BSA-adjusted eGFR

Laboratory eGFR is usually indexed to a standard body surface area of 1.73 m². For medication-related decisions, especially in very small or very large patients, clinicians may need nonindexed absolute eGFR in mL/min. The conversion is:

BSA adjustment formula

Absolute eGFR (mL/min) = indexed eGFR (mL/min/1.73 m²) × patient BSA / 1.73

Many drug labels still reference creatinine clearance or Cockcroft-Gault thresholds. Use this GFR calculator for modern kidney function reporting and CKD staging, and use the Creatinine Clearance Calculator when a label or protocol specifically requires Cockcroft-Gault CrCl.

CKD GFR Stage Classification

GFR category is one component of CKD classification. Persistent abnormality for at least three months and albuminuria category should also be considered.

G1: ≥90 — Normal or high G2: 60–89 — Mildly decreased G3a: 45–59 — Mild to moderate decrease G3b: 30–44 — Moderate to severe decrease G4: 15–29 — Severe decrease G5: <15 — Kidney failure

Evidence & sources

Frequently Asked Questions

eGFR, or estimated glomerular filtration rate, estimates kidney filtration from serum creatinine, age, and sex. It is reported in mL/min/1.73 m² and is used to stage chronic kidney disease, track kidney function trends, and support medication and trial decisions when paired with clinical context.
The 2021 CKD-EPI creatinine equation is widely recommended for adult eGFR reporting because it removes the race coefficient used in older equations and is more accurate than MDRD, especially at higher GFR values. NKF and KDIGO support race-free creatinine-based eGFR as the standard for laboratory reporting in adults.
CKD-EPI is the preferred modern equation for estimating GFR in adults. MDRD is a legacy equation that many laboratories used historically, but it is less accurate at higher GFR levels and may under-estimate kidney function in some patients. This calculator shows MDRD without the legacy race coefficient for reference.
Creatinine-based eGFR can be biased by muscle mass, diet, and acute illness. KDIGO notes that cystatin C–based or combined creatinine–cystatin C equations may be more accurate when muscle mass is atypical, when creatinine is changing rapidly, or when confirmation of reduced GFR is needed. Cystatin C is not a substitute for protocol-specific renal function definitions in drug trials.
Many drug labels and older protocols still specify Cockcroft-Gault creatinine clearance (CrCl) rather than eGFR. Use CrCl when the prescribing information, protocol, or regulatory submission explicitly requires it. eGFR is preferred for CKD staging and modern laboratory reporting; CrCl remains common for renally cleared drugs with legacy dosing tables.
KDIGO GFR categories are G1 (≥90), G2 (60–89), G3a (45–59), G3b (30–44), G4 (15–29), and G5 (<15 mL/min/1.73 m²). G1 and G2 alone do not define CKD unless kidney damage markers are also present. Full CKD classification combines GFR category with albuminuria (A1–A3) and cause of kidney disease.
Earlier CKD-EPI and MDRD equations included a Black race coefficient that increased eGFR estimates. In 2021, NKF-ASN task force recommendations and subsequent KDIGO guidance supported removing race from eGFR reporting to reduce bias and improve equity. The 2021 CKD-EPI creatinine equation applies the same formula to all adults regardless of race.
Oncology protocols often use eGFR or CrCl thresholds for eligibility, dose modification of renally cleared chemotherapies and supportive agents, and safety monitoring. Renal impairment cohorts in pharmacokinetic studies may stratify by eGFR category or measured GFR. Always apply the renal function definition specified in the protocol and prescribing information, not a generic calculator result alone.
For iodinated contrast, risk assessment considers acute kidney injury risk, baseline kidney function, volume status, and concurrent nephrotoxins—not eGFR alone. KDIGO and radiology society guidance use eGFR thresholds as one component of pre-procedure evaluation. Very low eGFR increases concern for post-contrast AKI; individualized assessment and hydration protocols apply.
CKD-EPI creatinine equations were developed and validated in adult populations. Children have different creatinine generation, body size, and growth patterns. Pediatric GFR estimation uses age-appropriate equations (such as Schwartz-based methods). This calculator is intended for adults aged 18 and older only.
Monitoring frequency depends on CKD stage, rate of change, comorbidities, and medications. KDIGO suggests more frequent testing when GFR is lower or declining, when albuminuria is present, or when starting or adjusting renally cleared drugs. Stable G3 or higher CKD typically warrants at least annual creatinine and eGFR; unstable or treated patients may need more frequent labs per nephrology or protocol guidance.
No. CKD requires markers of kidney damage or GFR <60 mL/min/1.73 m² for at least three months. A single low eGFR during acute illness, dehydration, or hospitalization does not establish CKD. Repeat testing, urine albumin-to-creatinine ratio, and clinical context are required before staging or long-term treatment decisions.

Related Calculators

CrCl Creatinine Clearance Dose Dosage Calculator BSA BMI / BSA Calculator QTc QTc Calculator CP Child-Pugh Score

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