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Schwartz Pediatric eGFR Calculator

Estimate pediatric kidney function from height and creatinine.

How it is calculated

The tool applies the bedside Schwartz equation with a single fixed constant: eGFR = 0.413 × height ÷ creatinine. Height is in centimetres, serum creatinine is in mg/dL, and the result is in mL/min/1.73 m². The constant 0.413 is used for every child: the tool does not ask for age or sex and does not switch constants. Height must be between 30 and 250 cm and creatinine between 0.1 and 25 mg/dL; anything outside those ranges shows no result. Creatinine must be entered in mg/dL; a value in µmol/L has to be divided by 88.4 first. The tool gives no normal range or stage of kidney disease. It is an estimate for screening and drug-dose discussion, and is not a diagnosis; interpretation belongs to the child's clinician.

Worked example

A child is 120 cm tall and has a serum creatinine of 0.6 mg/dL. Step 1: multiply the constant by the height: 0.413 × 120 = 49.56. Step 2: divide by the creatinine: 49.56 ÷ 0.6 = 82.6. The estimated GFR is 82.6 mL/min/1.73m². If the creatinine were twice as high at 1.2 mg/dL, the estimate would halve to 41.3, which shows how strongly the result depends on the creatinine value and why the creatinine must be entered in the correct unit.

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Common mistakes

  • Entering creatinine in µmol/L (for example 53) without converting. The tool expects mg/dL, and anything above 25 shows no result; 53 µmol/L is about 0.6 mg/dL, which gives roughly 83.
  • Entering height in metres (1.2) or inches. The field is in centimetres, and a height below 30 shows no result.
  • Expecting the tool to adjust for age or sex. It uses one constant, so it is the bedside form and not a version that varies by group.
  • Using this for adults. The formula was derived for children; adult eGFR needs a different equation.
  • Reading the number as a diagnosis. The tool shows no ranges or kidney disease stages, and a single value should be interpreted by a clinician along with the child's history.

Sources

About this calculator

The Schwartz formula estimates a child’s glomerular filtration rate (eGFR) — a key measure of kidney function — using height and serum creatinine, since the adult formulas used for eGFR (like CKD-EPI) aren’t valid for pediatric patients whose muscle mass and creatinine production change as they grow. The “bedside” Schwartz formula takes the form eGFR = (0.413 × height in cm) ÷ serum creatinine in mg/dL, and this calculator uses that single constant for every child; the original Schwartz formulas instead used a constant k that varied by age group and sex.

Pediatric nephrologists and pediatricians use this eGFR estimate to screen for chronic kidney disease, monitor kidney function over time, and adjust dosing for medications that are cleared renally, since a fixed adult reference range would misclassify a healthy child’s normal, still-developing kidney function. The formula was revised in 2009 (the “bedside Schwartz” or CKiD equation) to improve accuracy against measured GFR using modern, standardized creatinine assays.

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