How to Calculate GFR

What is GFR?

The estimated Glomerular Filtration Rate (eGFR) measures how well the kidneys filter waste from the blood. It is calculated from serum creatinine, age, and sex using the CKD-EPI 2021 equation (race-free version). eGFR is the primary metric for diagnosing and staging Chronic Kidney Disease (CKD).

Formula

CKD-EPI 2021: eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^(−1.200) × 0.9938^Age × (1.012 if female)

CKD: 142 × min(Scr/κ — 142 × min(Scr/κ
EPI: 142 × min(Scr/κ — 142 × min(Scr/κ

Step-by-Step Guide

1CKD-EPI 2021: eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^(−1.200) × 0.9938^Age × (1.012 if female)
2κ = 0.7 (female) or 0.9 (male); α = −0.241 (female) or −0.302 (male)
3Units: mL/min/1.73m² (normalised to average body surface area)
4A single eGFR < 60 for 3+ months defines CKD

Worked Examples

Input

Female, 55yo, creatinine 1.0 mg/dL

Result

eGFR ≈ 66 mL/min/1.73m² (G2)

Mildly decreased — monitor

Input

Male, 70yo, creatinine 2.0 mg/dL

Result

eGFR ≈ 32 mL/min/1.73m² (G3b)

Moderate-severe decrease

Frequently Asked Questions

What is Gfr?

How accurate is the Gfr calculator?

The calculator uses the standard published formula for gfr. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Gfr calculator use?

This calculator works with inches, square metres. You can enter values in the units shown — the calculator handles all conversions internally.

What formula does the Gfr calculator use?

The core formula is: CKD-EPI 2021: eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^(−1.200) × 0.9938^Age × (1.012 if female). Each step in the calculation is shown so you can verify the result manually.

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