CalcaTools

GFR Calculator

A GFR Calculator is a free online tool that estimates glomerular filtration rate using glomerular filtration rate, eGFR, kidney function test. Coaches, clinicians, and people tracking their health use it to set targets, track progress, and screen for risk against published guidance from National Kidney Foundation.

Last updated: June 2026 · Free · No sign-up required

Results

Enter values above and click Calculate to see your result instantly.

Quick reference

CKD stages by eGFR:

StageeGFR (mL/min/1.73m2)Kidney function
G190+Normal
G260–89Mildly reduced
G3a/G3b30–59Moderately reduced
G415–29Severely reduced
G5<15Kidney failure

monitor_weight A starting point, not a diagnosis

This calculator gives you the same number a clinician would compute by hand from your inputs. It is informational, never a substitute for a doctor. If a result surprises you, write it down and discuss it at your next appointment — that conversation is the goal, not a verdict from a webpage.

science Built from peer-reviewed formulas

Every health calculator on CalcaTools uses an equation from the WHO, NIH, ACOG, CDC, or a published peer-reviewed paper. The exact citation is in the "Formula & methodology" section. We re-check sources quarterly and update the page when guidance changes — the "Last reviewed" date is at the top.

volunteer_activism Designed for real people

Health calculations only help if you can actually use them. We use plain-English labels (no jargon), accept both metric and US units, and show what a "normal" range looks like alongside your result — so you understand what the number means, not just what it is.

lock Private by design

Your weight, height, age, pregnancy details, and any other health input never leave your browser. Calculations run client-side; nothing is logged or stored on our side. We don't want your medical data — we just want the formula to work for you.

Interpretation guide

eGFR inputs:

InputRole
Serum creatininePrimary marker (mg/dL)
AgeFunction declines with age
SexAdjusts the equation
2021 updateRemoved the race coefficient

Formula & methodology

Formula: 2021 CKD-EPI uses serum creatinine, age, and sex (no race term) to estimate GFR per 1.73m2

Estimated GFR gauges how well the kidneys filter blood, derived from serum creatinine, age, and sex using the 2021 CKD-EPI equation (which removed the earlier race coefficient). Results are normalized to a standard body surface area of 1.73 m2. Lower eGFR indicates reduced kidney function and maps to CKD stages. This is a screening estimate — diagnosis and management require a clinician and may use confirmatory testing.

Authoritative source: National Kidney Foundation

Frequently asked questions

What is eGFR?
Estimated glomerular filtration rate — a measure of kidney filtering capacity calculated from serum creatinine, age, and sex.
What is a normal GFR?
An eGFR of 90 or above is generally normal. 60–89 is mildly reduced; below 60 for three months suggests chronic kidney disease.
Why was the race coefficient removed in 2021?
The updated CKD-EPI equation dropped the race adjustment to provide more equitable, consistent estimates across populations.
What affects creatinine levels?
Muscle mass, hydration, diet, and certain medications can shift creatinine, which in turn affects the eGFR estimate.
Is this a diagnosis?
No. It's a screening estimate. Interpretation, staging, and treatment require a healthcare professional.