Financial term · Reviewed August 17, 2026
Glomerular filtration rate (GFR)
Glomerular filtration rate (GFR): A measure of how well the kidneys filter blood. It is usually estimated from a blood creatinine level, age and sex. Direct measurement is rare. The GFR Calculator returns this figure from 2021 CKD-EPI creatinine equation (race-free): 142 × min(scr/κ,1)^α × max(scr/κ,1)^-1.200 × 0.9938^age × 1.012 (if female). At that calculator’s documented worked-example inputs the estimated GFR (ml/min/1.73m²) is 94.6; holding every other input steady, moving serum creatinine from 0.8 to 1.2 moves it from 76 to 111.2, a spread of 35.2.
Clinicians use this to stage kidney function and to adjust the dose of drugs the kidneys clear. So it carries consequences well beyond one line on a lab report. Most reported values are estimates from a blood creatinine level plus age and sex, not direct measurements, and the estimating equations have been revised more than once.
| Term | Glomerular filtration rate (GFR) |
|---|---|
| Category | Clinical Estimates |
| How it is found | 2021 CKD-EPI creatinine equation (race-free): 142 × min(Scr/κ,1)^α × max(Scr/κ,1)^-1.200 × 0.9938^age × 1.012 (if female) |
| Worked example | Estimated GFR (mL/min/1.73m²): 94.6 |
| Computed by | GFR Calculator |
| Related terms | 3 defined in this glossary |
Before you rely on it
What to check
Note that it is estimated, and which equation was used.
The common error
Where people go wrong with glomerular filtration rate (GFR)
Reading a single value as a diagnosis. Muscle mass, diet, hydration and recent exercise all move creatinine, and interpretation belongs with a clinician who can see the trend and the context.
Worked through
Glomerular filtration rate (GFR) in plain numbers
A blood test reports serum creatinine. A formula combines it with age and sex to estimate GFR in mL/min per 1.73 m² of body surface area. Suppose the estimate comes out at 72. Clinical guidelines group results into stages: about 90 and above is normal or high, 60 to 89 is mildly decreased, 45 to 59 mildly to moderately decreased, 30 to 44 moderately to severely decreased, 15 to 29 severely decreased and below 15 kidney failure. A 72, on its own with no other sign of kidney damage, may not indicate disease; it is one input among others, and trends over time matter more than a single value.
Easily confused
Glomerular filtration rate (GFR) and its neighbours
Estimated GFR is not a measured GFR, and it is not the creatinine level itself. Creatinine is a waste product in the blood; the equation turns it into an estimate of filtering rate, adjusting for age and sex. Measured GFR requires specialized tests. Other markers, such as protein in the urine, and other equations, including ones that use cystatin C, give additional information. Kidney disease is diagnosed from several findings over time, not from one estimate.
In real decisions
Where glomerular filtration rate (GFR) turns up
Clinicians use eGFR to screen for and monitor kidney disease, to adjust the dose of some medicines and to time referrals; people with diabetes or high blood pressure are checked regularly. Researchers use it to study outcomes; a calculator lets someone see how the equation works and understand a lab report. Discussing results with a doctor is the appropriate next step, since interpretation depends on the whole picture.
Know the edges
Where glomerular filtration rate (GFR) stops being reliable
Equations are estimates and can be off in some people, such as those with very high or low muscle mass, certain diets or acute illness. Different equations give somewhat different numbers. A single result can be affected by hydration, recent meals or medicines. This page is for education and does not provide medical advice or a diagnosis, and anyone with concerns should talk with a qualified clinician.
Quick answers
What people ask about glomerular filtration rate (GFR)
Can I improve my eGFR? It depends on the cause. Controlling blood pressure and blood sugar, avoiding medicines that harm the kidneys and following medical advice can slow decline. Ask your clinician what applies to you.
Put it to work
How glomerular filtration rate (GFR) is calculated
At the GFR calculator’s worked-example inputs, estimated GFR (ml/min/1.73m²) is 94.6, percent of normal (90 ml/min) function is 105.1%. Moving serum creatinine from 0.8 to 1.2 moves that first figure from 76 to 111.2.
This is an educational estimate, not a laboratory test, a clinical diagnosis or a legal determination. Never use it to decide whether it is safe to drive or operate machinery, or to make a medical decision: consult a qualified professional.
Related vocabulary
Terms used alongside this one
Keep reading
Nearby in the glossary
- ← Gestational weight gain
- Grade point average (GPA) →
- All 174 defined termsThe complete Free Calculators Online financial glossary.