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Home/Calculators/GFR Calculator
Calculators

GFR Calculator

Estimate adult kidney filtration using race-free 2021 CKD-EPI equations, with documented lab units and non-diagnostic GFR categories.

  • ⚡FastRuns in your browser
  • ◆PrivateFiles stay on your device
  • ♥FreeNo account required

01 / INPUTS & ASSUMPTIONS

Choose values and calculation settings

Adult informational eGFR estimate only—not a diagnosis, medication dose or treatment recommendation. Do not use this calculator for pediatric patients or to determine care. Discuss lab results and clinical context with a healthcare professional.

Useful examples
  • NKF 2021 creatinine equation
  • NKF 2021 combined equation

02 / RESULT & EXPLANATION

Your calculated result

Estimated GFR · adult race-free equation68.6 mL/min/1.73 m²Calculations use the stated assumptions. Display rounding is separate from the calculation.
GFR category · not a diagnosis
G2
Method
2021 CKD-EPI creatinine
Creatinine normalized
1 mg/dL
Age and equation sex parameter
50 years · female

Medical information only—not a diagnosis, medication-dosing calculation or treatment recommendation. Adults 18+ only; no pediatric equation is implemented. CKD assessment needs clinical evidence, kidney-damage markers and persistence for at least 3 months. Estimates may be unreliable with acute kidney injury, unstable creatinine, unusual muscle mass, pregnancy or other clinical contexts. Discuss results with a healthcare professional.

Formula, worked steps & limitations
  1. eGFR = 142 × min(Scr/k,1)^a × max(Scr/k,1)^−1.200 × 0.9938^age × (1.012 if female).
  2. k = 0.7; a = -0.241; Scr is in mg/dL. Conversion convention: 88.4 µmol/L = 1 mg/dL.
  3. NKF equation transcription checked 2026-10-26. Creatinine should be IDMS-standardized; combined estimates also require standardized cystatin C. The sex parameter is the physiological coefficient used by the published equation, not a gender-identity assessment.
  4. Category uses the unrounded estimate; display rounding near a boundary does not establish a diagnosis.
GFR categories · not standalone CKD diagnoses
GFR categories · not standalone CKD diagnoses
CategoryeGFR (mL/min/1.73 m²)
G1≥90
G260–<90
G3a45–<60
G3b30–<45
G415–<30
G5<15

How to use GFR Calculator

  1. 1
    Choose the calculation mode and enter its values

    Enter your values locally; no inputs are uploaded.

  2. 2
    Review assumptions, units and validation, then Calculate

    Check validation feedback before reviewing the browser-generated result.

  3. 3
    Inspect the result and worked explanation, then copy or reset

    Review the explanation, copy supported outputs or reset the workspace.

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About GFR Calculator

Enter the values and units for gfr calculator, review the stated scope, then choose Calculate. Use the worked explanation and bounded tables to check the result; copy or reset locally.

Benefits

Use NKF-verified race-free adult equation coefficients with explicit standardized lab units, physiological equation parameters and non-diagnostic filtration categories.

Privacy note

GFR Calculator inputs and calculations remain in browser memory. No external processing service receives entered values. Existing website infrastructure may log ordinary page requests; copying occurs only when selected.

Frequently asked questions

Which eGFR equations are used?

The default is the adult race-free 2021 CKD-EPI creatinine equation. The optional combined method uses the 2021 creatinine–cystatin C equation. Formula coefficients were checked against the National Kidney Foundation sources on October 26, 2026.

How are creatinine units converted?

The documented convention is 88.4 µmol/L per 1 mg/dL. Creatinine entered in µmol/L is divided by 88.4 before the equation. Cystatin C is entered in mg/L.

What does the sex parameter represent?

It selects the physiological coefficient used in the published equation, not a gender-identity assessment. The calculator does not infer this input. Discuss which equation inputs are appropriate with a qualified clinician.

Does a GFR category diagnose chronic kidney disease?

No. G1 through G5 are filtration categories, not standalone diagnoses. CKD assessment requires clinical evidence, kidney-damage markers where applicable and persistence for at least three months. Display rounding near a boundary does not establish disease.

When can these estimates be unreliable?

Acute kidney injury, unstable creatinine, unusual muscle mass, pregnancy and other clinical contexts can make estimates unreliable. Standardized lab assays are required: IDMS-traceable creatinine and standardized cystatin C for the combined method.

Can this be used for children or medication dosing?

No. This implementation is adult informational scope only, ages 18–120, and does not implement a pediatric equation, absolute-GFR conversion, drug dosing or treatment recommendations. Confirm interpretation with a healthcare professional.