Pediatric GFR Calculator — Schwartz Formula (eGFR)
Calculate a child's estimated GFR (eGFR) using the Schwartz formula — the standard method for children aged 1–21 years. Enter height, serum creatinine, age, and sex to get eGFR in mL/min/1.73 m² and the corresponding CKD stage.
cm
mg/dL
years
Biological sex
Formula
CKD stage G2 — Mildly decreased (60–89) • k = 0.413
- 1
k factor
k = 0.413 = 0.413Bedside 2009 uses k = 0.413 for all children; classic formula adjusts for age and sex. - 2
k × height (cm)
0.413 × 120 = 49.56 - 3
eGFR = (k × height) ÷ Scr
49.56 ÷ 0.6 = 82.6
How does this calculator work?
Pediatric eGFR uses the Schwartz formula: Bedside 2009: 0.413 × Height (cm) / Scr (mg/dL) — preferred with modern enzymatic assays. Classic 1987: k × Height / Scr, where k = 0.45 (<1 yr), 0.55 (1–12 yr or female ≥13), 0.70 (male ≥13). Normal eGFR in children is 90–130 mL/min/1.73 m²; below 60 for ≥3 months indicates CKD.
Formula
How this is calculated
Creatinine is a muscle breakdown product that is freely filtered by the glomerulus and largely not reabsorbed, making its plasma concentration a proxy for how well the kidneys filter blood. In children, however, creatinine varies strongly with age and height because muscle mass grows throughout childhood. The Schwartz formula captures this by dividing a height-based factor (k × height) by the serum creatinine, normalising the result to a standard body surface area of 1.73 m².
The original Schwartz equation (1976, 1987) used age- and sex-specific k values calibrated to inulin clearance measurements with the Jaffé creatinine assay, which reads ~20% higher than modern enzymatic (IDMS-traceable) assays. The 2009 updated "bedside" formula — k = 0.413 for all children aged 1–16 years (Schwartz GJ et al., J Am Soc Nephrol 2009;20:629–637) — was recalibrated using iohexol plasma clearance (a gold-standard GFR method) and enzymatic creatinine measurements from the CKiD (Chronic Kidney Disease in Children) cohort study. The 2009 formula is the recommended choice when an enzymatic creatinine assay is used (which is now standard in virtually all laboratories).
Results are classified by KDIGO 2022 CKD stages: G1 (≥90, normal or high), G2 (60–89, mildly reduced), G3a (45–59), G3b (30–44), G4 (15–29, severely reduced), and G5 (<15, kidney failure). In children, a single eGFR result should always be interpreted alongside clinical context, urine dipstick and ACR, blood pressure, and growth trajectory. Transient illness, dehydration, and high dietary protein can acutely lower eGFR without reflecting chronic kidney disease.
Frequently asked questions
Children typically have eGFR values of 90–130 mL/min/1.73 m² — somewhat higher than the adult normal range (90–120) because of their relatively high cardiac output per unit body surface area. Values below 60 persisting for more than 3 months indicate CKD regardless of age. Reference ranges also depend on the formula used and the creatinine assay; the Bedside 2009 formula is calibrated to modern enzymatic assays.
Muscle mass increases rapidly in boys during puberty — creatinine production scales with muscle — so a given creatinine level reflects a lower fraction of GFR in adolescent males than in females of the same age. The higher k for males (0.70 vs 0.55) corrects for this, keeping the formula calibrated across sexes. The 2009 Bedside formula uses a single k = 0.413 and avoids this sex-specific adjustment by relying on a larger, more diverse calibration dataset.
The 2009 Bedside formula (k = 0.413) is preferred when serum creatinine is measured with an enzymatic (IDMS-traceable) assay, which is the current standard. The Classic 1987 formula was calibrated to the older Jaffé assay and will overestimate eGFR by ~20–30% if used with enzymatic creatinine values. Use the Classic formula only if you know the creatinine was measured by Jaffé method (increasingly rare after 2010).
Also known as
TG we-Calculate Editorial Team. (2026). Pediatric GFR Calculator — Schwartz Formula (eGFR) [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/pediatric-glomerular-filtration-rate-calculator
TG we-Calculate Editorial Team. "Pediatric GFR Calculator — Schwartz Formula (eGFR)." TG we-Calculate. 2026. https://we-calculate.com/calculator/pediatric-glomerular-filtration-rate-calculator.
TG we-Calculate Editorial Team, "Pediatric GFR Calculator — Schwartz Formula (eGFR)," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/pediatric-glomerular-filtration-rate-calculator
@misc{wecalculate_pediatric_glomerular_filtration_rate_calculator, title = {Pediatric GFR Calculator — Schwartz Formula (eGFR)}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/pediatric-glomerular-filtration-rate-calculator}}, year = {2026}, note = {TG we-Calculate} }
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