Estimate how well your kidneys filter blood from a serum creatinine result, with three formulas for adults and one for children.
For people aged 18 or older.
For people aged 18 or younger, using the Schwartz formula.
| Stage | GFR (mL/min/1.73 m²) |
|---|---|
| Normal | 90 or above, and no protein in the urine |
| CKD 1 | 90 or above, with evidence of kidney damage |
| CKD 2 (mild) | 60 to 89, with evidence of kidney damage |
| CKD 3 (moderate) | 30 to 59 |
| CKD 4 (severe) | 15 to 29 |
| CKD 5 (kidney failure) | under 15 |
| Age | Mean estimated GFR |
|---|---|
| 20–29 | 116 |
| 30–39 | 107 |
| 40–49 | 99 |
| 50–59 | 93 |
| 60–69 | 85 |
| 70 and over | 75 |
The glomerular filtration rate, or GFR, is the rate at which the kidneys filter blood, measured in millilitres per minute for a standard body surface area of 1.73 square metres. A higher number generally means the kidneys are working better. In healthy adults under 40 it is usually around 90 to 130, and it falls slowly with age. A GFR above 60 is usually enough for most people on its own, and a lasting drop below 60 can point to kidney disease.
GFR is rarely measured directly. Instead it is estimated from the level of creatinine in the blood, a waste product made by muscle, along with age and sex. This calculator shows three adult formulas: the MDRD equation, the CKD-EPI equation, and the Mayo Quadratic equation. They give similar answers for typical values and drift apart at the extremes, which is why all three are listed. For children it uses the Schwartz formula, which takes the child’s height in place of age and sex.
Compare the result with the stages table. Staging also depends on signs of kidney damage, such as protein in the urine, and on how long the low value lasts, so a single result is not a diagnosis. Creatinine can be higher after heavy meat meals, with a lot of muscle, or during illness and dehydration, and the formulas are less accurate for people with unusual muscle mass or diet. Always discuss your result with a doctor.
In adults under 40, a normal GFR is about 100 to 130 for men and 90 to 120 for women. It declines with age, and an estimated GFR of 60 or more is usually adequate.
The CKD-EPI and MDRD equations are the most common. The calculator shows MDRD, CKD-EPI and Mayo Quadratic together so you can compare them. Your doctor may prefer one of them.
Multiply mg/dL by 88.4 to get micromole/L, or divide micromole/L by 88.4 to get mg/dL. The calculator does this for you when you pick the unit.
The Schwartz formula for children uses height and creatinine. Height stands in for body size and muscle mass, which change as a child grows.
Yes. Dehydration, illness and some medicines can lower GFR for a short time. Chronic kidney disease is diagnosed when a low value lasts for three months or more.
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