GFR Calculator | Glomerular Filtration Rate Formula

What is Glomerular filtration rate (GFR)?

The estimated glomerular filtration rate(eGFR)is a measurement that determines the risks of developing renal disease. It may be estimated using the results of your blood tests. If the result is low, it could mean your kidneys aren't working properly; in the worst-case, you could have chronic renal disease. The earlier it is identified then there are better chances for an effective treatment.

The unit of eGFR is mL/min/1.73m². The standardized body area is 1.73m2, so none of the calculations involve a height or weight variable.

CKD-EPI Creatinine Equation (2021)

This is the most common and recommended technique to find the estimated glomerular filtration rate. It only takes one serum creatinine result from a blood test.

eGFR = 142 * min(SCr/k, 1)^α * max(SCr/k, 1)^-1.209 * 0.993^Age * a * b

where:

α be a coefficient dependent on gender: -0.329 for females, -0.411 for males;
k be a coefficient dependent on gender: 0.7 for females, 0.9 for males;
a be a coefficient dependent on gender: 1.018 for females, 1 for males;
b be a coefficient dependent on race: 1.159 for black, 1 for other; and
SCr is the level of standardized serum creatinine is measured in mg/dL.

The table describes the common eGFR levels at various stages of kidney failure based on data provided by the National Renal Foundation.

eGFR [mL/min/1.73m²]	Kidney function
90 or above	No kidney failure or mild kidney damage
60-89	Kidney failure with mild loss of kidney function
45-59	Mild to moderate loss of kidney function
30-45	Moderate to severe loss of kidney function
15-29	Severe loss of kidney function
Less than 15	Kidney failure

You can go through the following examole for a better understanding to calculate the GRF of the specified person using this tool and for more concepts by visiting the site called arithmeticcalculator.com

Steps to Use GFR Calculator

Enter Serum creatinine result from blodd test report, age, gender and race details.
Tap on the calculate button.
Chronic Kidney Disease Stages, GFR results based on 3 different formulas are available on the result page.

Example on GFR

1. Calculate the estimated glomerular filtration rate(eGFR) whose serum creatinine is 45 mg/dL and the women's age is 32 and the ethnicity is black.

Solution:

Given that,

Serum creatinine is 45 mg/dL

Age is 32

Ethnicity is black

Formula used:

eGFR = 142 * min(SCr/k, 1)^α * max(SCr/k, 1)^-1.209 * 0.993^Age * a * b

where:

α be a coefficient dependent on gender: -0.329 for females, -0.411 for males;
k be a coefficient dependent on gender: 0.7 for females, 0.9 for males;
a be a coefficient dependent on gender: 1.018 for females, 1 for males;
b be a coefficient dependent on race: 1.159 for black, 1 for other; and
SCr is the level of standardized serum creatinine is measured in mg/dL.

eGFR = 142 * min(45/0.7, 1)^-0.329 * max(45/0.7, 1)^-1.209 * 0.993² * 1.018 * 1.159

eGFR = 0.87 mL/min/1.73m²

Therefore, the estimated glomerular filtration rate is 0.87 mL/min/1.73m².

FAQs on Free Online GFR (glomerular filtration rate) Calculator

1. Why is eGFR testing performed?

Early stage kidney disease normally has no symptoms, but if you are at a higher risk of developing kidney disease, your doctor may recommend an eGFR test. The following are some of the risk factors for CKD:

Diabetic or hypertensive disorders
High BP
Being overweight is a concern.
Kidney failure in the families

2. What does your GFR Mean?

The glomerular filtration rate (GFR) of a healthy kidney is about 100, which shows that the kidneys are functioning correctly. If your GFR is 90 or above, your kidney function is still considered normal. Your kidneys are functioning at around 45 percent of their regular pace if your GFR is 45.

3. How do you find out how much blood you have in your body?

GFR is a measure of how well your kidneys work. The sum of all your working nephrons filtration rates that is called GFR. GFR = 140 – [your age] is an equation that may be used to calculate an estimate of your GFR normal value.

4. What is the method of dealing with chronic renal disease?

You may have chronic kidney disease if you have some of the CKD symptoms, such as a reduced eGFR or alarming signs in your urine that last longer than three months. Diabetes or excessive blood pressure are the root causes in two out of every three instances.