GFR Calculator
The GFR (glomerular filtration rate) Calculator estimates GFR values from serum creatinine, age, gender, and race. For comparison, the adult results are given for three prevalent formulas — MDRD, CKD-EPI, and the Mayo Quadratic — while children are estimated with the Schwartz formula from height and creatinine.
GFR Calculator for Adults
For people aged 18 years or older.
The following are the GFR results based on 3 formulas often used:
GFR Calculator for Children
For people aged 18 years or younger — Schwartz formula.
GFR = mL/min/1.73 m2
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(Responsive Fluid)
What is glomerular filtration rate (GFR)?
GFR describes how fast fluid is filtered through the kidneys, and it is the standard yardstick of kidney function: higher is generally better, and a significant fall means the kidneys are filtering less volume per unit time than they should. Adjusted for body surface area, the normal range is 100 to 130 mL/min/1.73 m2 in men and 90 to 120 mL/min/1.73 m2 in women under 40; after 40, GFR declines progressively with age.
Population mean estimated GFR
| Age | Mean Estimated GFR (mL/min/1.73 m2) |
|---|---|
| 20-29 | 116 |
| 30-39 | 107 |
| 40-49 | 99 |
| 50-59 | 93 |
| 60-69 | 85 |
| 70+ | 75 |
Chronic kidney disease stages
A GFR above 60 mL/min/1.73 m2 is usually adequate, and on its own does not mean chronic kidney disease (CKD).1 A significant decline since a previous test, though, can be an early indicator — and the earlier kidney disease is caught and treated, the better the chance of avoiding dialysis. Stages combine the GFR range with evidence of kidney damage, as noted:
| Stage | GFR Value (mL/min/1.73 m2) |
|---|---|
| Normal | 90+ or above and no proteinuria |
| CKD1 | 90+ with evidence of kidney damage |
| CKD2 (Mild) | 60 to 89 with evidence of kidney damage |
| CKD3 (Moderate) | 30 to 59 |
| CKD4 (Severe) | 15 to 29 |
| CKD5 Kidney failure | less than 15 |
Measuring GFR
The most accurate measurement is inulin clearance: inulin is freely filtered and is neither metabolized, secreted, nor reabsorbed, which makes it ideal — but the test needs continuous intravenous infusion with repeated, carefully timed blood and urine collections, so it is impractical for routine care.2,3 Everyday practice therefore estimates GFR from serum creatinine. Creatinine clearance has real limits: muscle mass moves serum creatinine independently of kidney function, and because the body secretes a little creatinine, clearance based on it typically overestimates GFR by 10-20%. It remains in use because it is easy. Three widely used estimating equations, plus the children's formula, are:
The IDMS-traceable MDRD study equation
GFR = 175 × (SCr)-1.154 × (age)-0.203 × (0.742 if female) × (1.212 if Black), with SCr in mg/dL.
The CKD-EPI formula
GFR = A × (SCr/κ)α × 0.993age, where κ is 0.7 for females and 0.9 for males; α is -0.329 (female) or -0.411 (male) when SCr ≤ κ and -1.209 when SCr > κ; and A is 144 (non-Black female), 166 (Black female), 141 (non-Black male), or 163 (Black male).
The Mayo Quadratic formula
If SCr < 0.8 mg/dL, use 0.8 mg/dL. GFR = e(1.911 + 5.249/SCr − 2.114/SCr2 − 0.00686 × age − (0.205 if female)).
Estimated GFR for children — Schwartz formula
GFR = 0.413 × height (in cm) / SCr.
- "Normal GFR," The UK eCKD Guide, The Renal Association.
- Gaspari, F., Perico, N., Remuzzi, G. 1997. "Measurement of glomerular filtration rate." Kidney International Supplements 63: S151-4. PMID 9407445.
- Hsu, C., Bansal, N. 2011. "Measured GFR as 'Gold Standard' – All that Glitters Is Not Gold?" Clinical Journal of the American Society of Nephrology 6(8): 1813-14. doi:10.2215/CJN.06040611.