eGFR Calculator

What is eGFR?

eGFR stands for estimated glomerular filtration rate. It shows how well your kidneys are filtering waste from your blood, measured in millilitres per minute per 1.73 square metres of body surface area (mL/min/1.73m²). Healthy kidneys filter about 90–120 mL of blood per minute. Because measuring filtration directly is complicated, doctors estimate it from a simple blood test for creatinine, a waste product made by your muscles and cleared by your kidneys.

When the kidneys are not working well, creatinine builds up in the blood and eGFR goes down. eGFR is the main test used to detect and stage chronic kidney disease (CKD).

The CKD-EPI 2021 equation

This calculator uses the CKD-EPI 2021 creatinine equation, recommended by the US National Kidney Foundation and the American Society of Nephrology. Unlike older equations, it does not use race, and it is now the standard used by many laboratories.

eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−1.200 × 0.9938^age × 1.012 [if female]

Where Scr is serum creatinine in mg/dL, κ is 0.7 for women and 0.9 for men, and α is −0.241 for women and −0.302 for men. If your result is in µmol/L, divide by 88.4 to convert to mg/dL. The calculator does this for you.

Examples: A 50-year-old man with a creatinine of 1.0 mg/dL has an eGFR of about 92 (stage G1). A 60-year-old woman with a creatinine of 1.2 mg/dL has an eGFR of about 52 (stage G3a).

CKD stages by eGFR

The international KDIGO guidelines group kidney function into these stages:

Stage	eGFR (mL/min/1.73m²)	Kidney function
G1	90 or above	Normal or high
G2	60–89	Mildly decreased
G3a	45–59	Mildly to moderately decreased
G3b	30–44	Moderately to severely decreased
G4	15–29	Severely decreased
G5	Below 15	Kidney failure

Chronic kidney disease is diagnosed when eGFR stays below 60 for more than three months, or when there are other signs of kidney damage, such as protein (albumin) in the urine, even with a higher eGFR. Doctors also check a urine albumin-to-creatinine ratio (ACR) to get the full picture.

What is a normal eGFR by age?

Kidney function naturally declines slowly with age, by roughly 1 mL/min per year after about age 40. A young adult typically has an eGFR above 100, while many healthy people over 70 have an eGFR between 60 and 80. A mildly reduced eGFR in an older person without other signs of kidney damage is often a normal part of ageing, but it is still worth monitoring.

When eGFR may be less accurate

Because creatinine comes from muscle, eGFR can be misleading in people with very high or very low muscle mass, such as bodybuilders, people with amputations or those who are very frail. It is also less reliable during sudden kidney injury, when creatinine is changing quickly, in pregnancy, in children, and after eating a large amount of cooked meat or taking creatine supplements. In these cases, doctors may use a cystatin C blood test or measure kidney function more directly.

How to protect your kidneys

The most common causes of kidney disease are diabetes and high blood pressure, so keeping blood sugar and blood pressure under control is the most important step. Other helpful steps include staying well hydrated, keeping a healthy weight, eating less salt, not smoking, and avoiding regular use of painkillers such as ibuprofen and diclofenac without medical advice. People with diabetes, high blood pressure or a family history of kidney disease should have their eGFR and urine checked regularly. You can use our BMI Calculator to check your weight and the Water Intake Calculator to plan your daily fluids.

Frequently Asked Questions

What is a normal eGFR?

An eGFR of 90 or above is normal. An eGFR of 60–89 can also be normal, especially in older adults, if there are no other signs of kidney damage. An eGFR below 60 for more than three months suggests chronic kidney disease.

What eGFR level is dangerous?

An eGFR below 30 means kidney function is severely reduced and needs specialist care. An eGFR below 15 is classed as kidney failure, where dialysis or a kidney transplant may be needed.

Can eGFR improve?

Yes, in some cases. eGFR can rise after recovery from dehydration or a short-term illness, or when blood pressure and blood sugar are better controlled. In chronic kidney disease, the main goal is usually to slow further decline.

Why does this calculator not ask for race?

The CKD-EPI 2021 equation removed race from the calculation, following recommendations from kidney specialists. It gives accurate results for people of all backgrounds without a race adjustment.

How do I convert creatinine from µmol/L to mg/dL?

Divide the value in µmol/L by 88.4. For example, 88 µmol/L is about 1.0 mg/dL. You can also use the µmol/L option in this calculator.

Can I use this eGFR calculator for children?

No. The CKD-EPI equation is designed for adults aged 18 and over. Children need a different formula, such as the bedside Schwartz equation, which uses height.