Rex says
Same equations the textbooks use — just way less awkward. Pop in your stats and I'll tell you what the number actually means for you.
Try a scenario
Click to load — tweak from there.Inputs
Result
eGFR (mL/min/1.73 m²)
79.3
CKD stage
G2
Percent of typical function
79%
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter serum creatinine (mg/dL).
- 2Enter age (yr).
- 3Enter sex.
- 4Read your egfr (ml/min/1.73 m²) on the right — it updates as you type.
- 5Hit Share to keep the scenario or send it to someone.
About this calculator
Estimate kidney filtration using the CKD-EPI 2021 creatinine equation, which no longer applies a race coefficient, and see the corresponding chronic kidney disease stage.
Worked example
Using the values the calculator loads with:
Inputs
- Serum creatinine: 1.1 mg/dL
- Age: 55 yr
- Sex: Male
Results
- eGFR (mL/min/1.73 m²): 79.3
- CKD stage: G2
- Percent of typical function: 79%
What each field means
Inputs
- Serum creatinine (mg/dL)
- The serum creatinine used in the calculation, measured in mg/dL. Starts at 1.1 mg/dL so you have a working example on load.
- Age (yr)
- The age used in the calculation, measured in yr. Starts at 55 yr so you have a working example on load. Accepted range: 18–110 yr.
- Sex
- Pick the option that matches your situation — the maths changes per option. Choices: Male, Female.
Results
- eGFR (mL/min/1.73 m²)
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- CKD stage
- Returned as a plain value. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Percent of typical function
- Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Why no race coefficient?
The 2021 CKD-EPI refit removed it. Race is a social category, not a biological determinant of creatinine generation, and the coefficient delayed care for Black patients.
Is a single value diagnostic?
No. Chronic kidney disease requires abnormality persisting over three months, plus context like albuminuria.
Accuracy and limitations
- Population formulas describe averages; individual bodies vary, especially at the extremes of height, age, or muscle mass.
- Results do not account for medical conditions, medication, or pregnancy.
- Use this as a directional reference, not a diagnosis — talk to a clinician before acting on it.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). eGFR Kidney Function Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/egfr
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/egfr" target="_blank" rel="noopener">eGFR Kidney Function Calculator — RevenueLab</a> (2026).</p>
Source: [eGFR Kidney Function Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/egfr) (2026).