GFR Calculator (CKD-EPI 2021)

Estimate glomerular filtration rate from creatinine, age, sex, and race-free CKD-EPI equation.

Written by

Sid A. Abdala Balal

RGN · Medical & Nursing Content Author

Medically reviewed by

Dr. Adam Sayedi

MD · Emergency & Acute Medicine

⚠️ Safety note: Renal dosing: eGFR supports context only — confirm renally cleared drug doses with pharmacy and local renal-dosing guidance.

Understanding this tool

Why nurses use it

Estimated GFR (eGFR) from creatinine supports CKD staging, renal dosing context, and contrast discussions. CKD-EPI 2021 is the race-free equation recommended by NKF/ASN.

When to use it

Use with stable creatinine for chronic kidney context — not during acute kidney injury when creatinine is changing rapidly.

Calculate

How to use this calculator

Enter age, sex, and serum creatinine (use unit selector if µmol/L).
Note eGFR and CKD stage context.
Confirm drug dosing with pharmacy and renal dosing references.

How the calculation works

CKD-EPI 2021 uses creatinine, age, and sex with separate coefficients — it estimates ml/min/1.73m² filtered through standardised kidney function indexing.

CKD-EPI 2021 creatinine equation

Formula used by this tool — verify units before applying at the bedside.

Worked example

Female, 65 y, Cr 1.2 mg/dL → eGFR approximately 50 mL/min/1.73m² (verify with lab report).

Limitations & clinical notes

CKD-EPI 2021 race-free equation; not validated for acute kidney injury.
Drug dosing may use CrCl or eGFR per specific medication guidance.

References

Key sources: NKF/ASN CKD-EPI 2021.

Disclaimer: This calculator is for educational and bedside double-check purposes only. It does not replace institutional protocols, prescriber orders, pharmacist verification, or clinical judgment. Always follow your local policies — especially for high-risk medications, infusions, pediatrics, and critical care. If the patient is acutely unwell, escalate immediately rather than relying on any calculator output.