What is the Schwartz formula?

The Schwartz formula estimates GFR as: eGFR = k × height (cm) / serum creatinine (mg/dL). The k constant varies by age and sex to account for differences in muscle mass relative to body size.

What k values are used?

Typical k values: 0.33 for preterm infants, 0.45 for full-term infants (≤1 year), 0.55 for children aged 2–12, 0.55 for adolescent girls, and 0.70 for adolescent boys.

Height must be entered in centimeters, serum creatinine in mg/dL. The result is expressed as mL/min/1.73 m².

How accurate is this formula?

The original 1976 Schwartz formula is widely validated for children. A 2009 "bedside" revision uses k=0.413 for all children when creatinine is measured with isotope dilution mass spectrometry (IDMS). This tool uses the classic k values; consult your lab for the creatinine assay used.

Can this be used for adults?

No. The Schwartz formula is validated for patients from birth through approximately 18 years of age. For adults, use the CKD-EPI or MDRD equations instead.

What is a normal GFR in children?

Normal eGFR in children is generally ≥90 mL/min/1.73 m² after infancy. Neonates and infants have lower values that increase rapidly in the first two years of life.

Schwartz Pediatric GFR Calculator

Calculate estimated GFR in children using the Schwartz formula with age-appropriate k constants.

Patient Details

Age Group

k constant: 0.45

Height (cm)

Serum Creatinine (mg/dL)

Result

Enter the values and click Calculate.

Schwartz k Constant Reference

Age / Group	k Value	Notes
Preterm infant	0.33	Lower muscle mass, gestational correction needed
Full-term infant (≤1 year)	0.45	Both sexes
Child (2–12 years)	0.55	Both sexes
Adolescent girl (13–18 years)	0.55	Lower muscle mass than males
Adolescent boy (13–18 years)	0.70	Higher muscle mass at puberty

Summary

The Schwartz formula estimates glomerular filtration rate (eGFR) in children from birth through adolescence using serum creatinine and height. It applies an age- and sex-based constant (k) to account for differences in muscle mass across developmental stages. This tool is widely used clinically to monitor kidney function in pediatric patients.

How it works

Select the patient age group (and sex where relevant) to determine the correct k constant.
Enter the child's height in centimeters.
Enter the serum creatinine level in mg/dL.
The calculator applies eGFR = k × Height (cm) / Serum Creatinine (mg/dL).
Results are displayed in mL/min/1.73 m² with a CKD stage interpretation.

Use cases

Screening for chronic kidney disease (CKD) in pediatric patients.
Monitoring kidney function in children with known renal conditions.
Calculating drug dosing adjustments in pediatric nephrology.
Tracking eGFR trends over time in children with recurrent UTIs or other renal conditions.
Educational tool for medical students learning pediatric renal physiology.
Supporting clinical decisions in neonatal intensive care units.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu