About the Pediatric eGFR (Schwartz) Calculator
Adult kidney-function equations such as CKD-EPI do not work in children, whose creatinine production rises with muscle mass as they grow. The bedside Schwartz equation, published by the Chronic Kidney Disease in Children (CKiD) study in 2009, estimates glomerular filtration rate from just two numbers: height in centimetres and serum creatinine in mg/dL, multiplied by 0.413. It assumes an enzymatic (IDMS-traceable) creatinine assay, which is what most labs now use.
This calculator gives the bedside Schwartz result as the headline figure and, alongside it, the newer CKiD under-25 (U25) creatinine equation from 2021, which uses an age- and sex-dependent constant and is designed to bridge smoothly into young adulthood. It also places the result in a KDIGO GFR category to help frame the number.
The bedside Schwartz equation was developed in 349 children aged 1 to 16 with chronic kidney disease (median measured iohexol GFR about 41 mL/min/1.73 m²), so it is less accurate at normal or high GFR, in infants under 1 year, and when kidney function is changing quickly, as in acute kidney injury. It is a clinical estimate, not a measured GFR.
With the default inputs, the egfr — bedside schwartz is 82.6 mL/min/1.73 m². Change any value above to recalculate instantly.
How to use the pediatric egfr (schwartz) calculator
- 1Enter the child’s measured height and choose cm or inches.
- 2Enter the serum creatinine and its unit.
- 3Add age and sex to see the CKiD U25 estimate as well.
- 4Read the bedside Schwartz eGFR and its KDIGO GFR category.
- 5Compare the two equations and interpret alongside urine tests and the clinical picture.
Formula and method
The bedside Schwartz equation multiplies height in centimetres by 0.413 and divides by serum creatinine in mg/dL, giving GFR in mL/min/1.73 m². Taller children have more muscle and so produce more creatinine, which is why height appears in the numerator. The 0.413 constant replaced the older 0.55 when labs switched to enzymatic, IDMS-calibrated creatinine assays.
The CKiD U25 equation (Pierce 2021) uses height in metres and a constant K that depends on age and sex. For males, K = 39.0 × 1.008^(age − 12) under 12, 39.0 × 1.045^(age − 12) from 12 to 18 and 50.8 from 18 to 25. For females, K = 36.1 × 1.008^(age − 12) under 12, 36.1 × 1.023^(age − 12) from 12 to 18 and 41.4 from 18 to 25. The GFR category uses the KDIGO bands G1–G5.
- SCr
- Serum creatinine (mg/dL; µmol/L ÷ 88.4)
- height
- Height in cm (bedside) or metres (U25)
- K
- Age- and sex-specific CKiD U25 constant
Worked examples
8-year-old boy, 120 cm, creatinine 0.6 mg/dL
Bedside Schwartz: 0.413 × 120 ÷ 0.6 = 82.6 mL/min/1.73 m², category G2. For the U25 equation, K = 39.0 × 1.008⁻⁴ = 37.78, so eGFR = 37.78 × 1.20 ÷ 0.6 = 75.6.
14-year-old girl, 160 cm, creatinine 88 µmol/L
88 µmol/L ÷ 88.4 = 0.995 mg/dL. Bedside Schwartz: 0.413 × 160 ÷ 0.995 = 66.4. For a 14-year-old female, K = 36.1 × 1.023² = 37.78, giving 37.78 × 1.60 ÷ 0.995 = 60.7 mL/min/1.73 m².
Child with advanced CKD, height in inches
50 inches is 127 cm. Bedside Schwartz gives 0.413 × 127 ÷ 2.5 = 21.0 mL/min/1.73 m², in the G4 (severely decreased) range.
Frequently asked questions
What is the bedside Schwartz equation?+
It is eGFR = 0.413 × height (cm) ÷ serum creatinine (mg/dL), published by Schwartz and colleagues in 2009 from the CKiD cohort. It is the most widely used pediatric creatinine-based GFR estimate.
Why 0.413 and not 0.55?+
The original 1976 Schwartz formula used k = 0.55 with the older Jaffe creatinine method. Modern enzymatic, IDMS-traceable assays read lower, so the 2009 update recalibrated the constant to 0.413 against measured iohexol GFR.
What is a normal GFR for a child?+
After about age 2, a normal GFR is similar to adults, roughly 90–130 mL/min/1.73 m². Newborns and infants have much lower values that mature over the first two years, so adult categories should not be applied to infants.
When should I use the CKiD U25 equation?+
The 2021 CKiD U25 equation covers ages 1 to 25 and uses an age- and sex-specific constant, reducing bias in young children and young adults. It is useful for adolescents moving into adult care, where switching to an adult equation can cause an artificial jump.
Can I use Schwartz in acute kidney injury?+
Creatinine-based estimates assume stable kidney function. In acute kidney injury creatinine lags behind the true GFR, so any eGFR, including Schwartz, can overestimate kidney function until creatinine plateaus.
For healthcare professionals and education only. This calculator implements a published formula or score but is not a diagnosis and does not replace clinical judgment. Verify inputs and results against the original source before using them in patient care.