In children, Cockcroft-Gault does not apply: it was built for adults and depends on adult weight and age relationships. The standard pediatric estimate is the bedside Schwartz equation: eGFR = 0.413 × height (cm) ÷ serum creatinine (mg/dL), reported in mL/min/1.73m². The calculator above applies it for children and adolescents. Strictly, the result is an estimated GFR rather than a creatinine clearance, but in children it fills the role that the Cockcroft-Gault CrCl plays in adults.
How to Use the Pediatric Calculator
- Enter the child's height in cm or inches. Inches are converted to cm (× 2.54) before the equation runs.
- Enter a current serum creatinine in mg/dL or µmol/L. µmol/L is divided by 88.4 to give mg/dL.
- Read the eGFR in mL/min/1.73m² with its KDIGO GFR category, and check the result against the child's age and growth.
Why Adult Formulas Fail in Children
Adult formulas fail in children because a child's body composition keeps changing. Muscle mass (the source of creatinine) changes rapidly with growth, so the fixed weight-and-age coefficients that work for adults do not map onto a growing child. A toddler and a teenager with the same serum creatinine have very different kidney function. The Schwartz equation sidesteps the problem by using height as a stand-in for muscle mass, which tracks body size far more reliably across the pediatric age range. Normal creatinine values are also much lower in children, which is expected and not a sign of unusually strong kidneys.
The Bedside Schwartz Equation
Schwartz and colleagues published the bedside equation in 2009 using data from 349 children aged 1 to 16 years in the Chronic Kidney Disease in Children (CKiD) cohort, with GFR measured by iohexol clearance. It replaced the original 1970s Schwartz formula, which had come to overestimate GFR after laboratories changed the way they measure creatinine. It estimates eGFR (mL/min/1.73m²) from a child's height and creatinine:
eGFR = 0.413 × height (cm) ÷ serum creatinine (mg/dL)
For example, a child 120 cm tall with a creatinine of 0.5 mg/dL has an estimated eGFR of about 99 mL/min/1.73m² (0.413 × 120 ÷ 0.5). A taller child of 150 cm with the same 0.5 mg/dL estimates near 124 mL/min/1.73m², while a shorter child of 90 cm with a creatinine of 0.4 mg/dL lands around 93 mL/min/1.73m². Height moves the result as much as creatinine does.
Reading a Child's eGFR
Normal kidney function in children climbs through the first years of life and reaches the adult reference of roughly 90 mL/min/1.73m² or higher by about age two. After that, the same broad bands used in adults apply, but interpretation always accounts for the child's age and growth. A value that would be ordinary in an adult may be low for a healthy school-age child, so pediatric results are read against age-appropriate expectations rather than a single fixed cutoff. The 1.73 m² in the units is a standard adult body-surface-area normalization, which lets a small child's filtration be compared on the same scale.
Why an Accurate Height Matters
Because height sits in the numerator of the Schwartz equation, a measurement error feeds directly into the result. A child recorded as 5 cm taller than they are will have their eGFR overstated in proportion. Using a recent, carefully measured standing height (or recumbent length in infants) and a current creatinine from a standardized assay is therefore essential. Stale or estimated heights are one of the most common reasons a pediatric eGFR comes out wrong.
When the Estimate Needs Care
Bedside Schwartz assumes a standard creatinine assay and a child who is growing normally. It is less dependable at the extremes: in very young infants, in children with unusual body builds, or when creatinine is changing rapidly. In those situations a clinician may turn to a cystatin C-based estimate or a measured clearance. The number guides care but does not replace clinical judgment.
Dosing Medications in Children
Pediatric drug dosing leans on the Schwartz estimate together with the child's weight, since most pediatric doses are weight-based to begin with. When a drug is cleared by the kidneys, the eGFR guides whether the dose or interval needs adjusting for reduced function. Because a child's creatinine values are naturally low, it is easy to misread a result without the height-based context Schwartz provides. That is why the adult formulas are set aside in children.
See the full method on the Schwartz equation page, and learn how eGFR is interpreted.