Pediatric GFR Calculator - Glomerular Filtration Rate

Estimate a child's glomerular filtration rate from height and serum creatinine using the bedside Schwartz formula, then see the corresponding CKD stage.

Quick Facts

Formula
Bedside Schwartz equation
GFR = 0.413 x height (cm) / serum creatinine (mg/dL); published 2009, calibrated to enzymatic creatinine assays.
Typical range
~90-150 mL/min/1.73m²
Applies from about age 2 onward; GFR is naturally lower in infants under 2 as kidneys are still maturing.

Your Results

Calculated
Estimated GFR
-
mL/min/1.73m² (bedside Schwartz)
CKD stage
-
KDIGO-style G1-G5 category
Constant used (k)
-
Applied in the formula above
Height:creatinine ratio
-
cm per mg/dL, before k is applied

Ready

Enter height, creatinine, and age, then calculate the estimated GFR.

About the pediatric GFR calculator

Glomerular filtration rate (GFR) estimates how well the kidneys filter blood, and it changes with normal growth in children, which is why adult formulas do not apply directly to pediatric patients. This calculator uses the bedside Schwartz equation, the equation most widely adopted for children since its 2009 publication, along with the classic 1976 Schwartz constants for situations that call for them.

The formula

The bedside Schwartz equation is:

GFR (mL/min/1.73m²) = 0.413 x height (cm) / serum creatinine (mg/dL)

Height is measured in centimeters and serum creatinine in mg/dL, drawn from a standard metabolic panel. The constant 0.413 was derived from the Chronic Kidney Disease in Children (CKiD) cohort and calibrated to creatinine measured by an enzymatic assay, the method most labs use today.

When the original constants apply

Before 2009, the original Schwartz formula used a constant that varied by age and sex, calibrated to the older Jaffe creatinine assay: 0.33 for low-birth-weight infants under 1 year, 0.45 for full-term infants under 2 years, 0.55 for children and adolescent females (and males under 13), and 0.70 for adolescent males 13 to 18. Select the matching group in the calculator if your lab still reports Jaffe-method creatinine or you need to compare against older records.

Reading the CKD stage

The calculator maps the estimated GFR onto the same G1-G5 staging bands used in adult chronic kidney disease: G1 is 90 and above, G2 is 60-89, G3a is 45-59, G3b is 30-44, G4 is 15-29, and G5 is below 15. These bands are most meaningful for children age 2 and older; infants have physiologically lower GFR because kidney maturation continues through the first two years of life, so the same numeric bands are less standardized at that age.

When to consult a professional

This calculator performs the standard Schwartz arithmetic for education and tracking. It does not diagnose kidney disease or guide medication dosing. Any result that looks abnormal, or any decision about treatment or drug dosing, should go through a pediatrician or pediatric nephrologist who can weigh the estimate against the child's full clinical picture.

Frequently Asked Questions

What formula does this calculator use?
This calculator uses the bedside Schwartz equation, the current standard for estimating pediatric glomerular filtration rate: GFR (mL/min/1.73m²) = 0.413 x height (cm) / serum creatinine (mg/dL). Published in 2009 from the CKiD cohort, it is calibrated to creatinine measured by an enzymatic assay and is intended for children roughly ages 1 to 18.
What do the CKD stages mean?
The stages follow the same G1-G5 bands used in adults: G1 is 90 or above (normal or high), G2 is 60-89 (mildly decreased), G3a is 45-59, G3b is 30-44, G4 is 15-29, and G5 is below 15 (kidney failure). These bands are most meaningful for children 2 years and older; GFR is naturally lower in infants because kidney maturation is not complete until about age 2.
When should I use a different k constant?
The bedside constant, 0.413, is the modern default for most children and adolescents whose creatinine is measured by an enzymatic assay. The original 1976 Schwartz formula used different constants by age and sex - 0.33 for low-birth-weight infants under 1 year, 0.45 for full-term infants under 2 years, 0.55 for children and adolescent females (and males under 13), and 0.70 for adolescent males 13 to 18 - intended for creatinine measured by the older Jaffe method.

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