Pediatric GFR Calculator (bedside Schwartz equation for children)

Understanding the pediatric GFR calculator (bedside Schwartz) — concept and principle

This calculator estimates a child's glomerular filtration rate (GFR), the main measure of kidney function, from height and serum creatinine using the bedside Schwartz equation (2009). Paediatricians use it to check kidney function, adjust medicine doses and follow chronic kidney disease.

Bedside Schwartz: with the default inputs the result is 105.7 (mL/min/1.73 m²).

How it is calculated

eGFR (mL/min/1.73 m²) = 0.413 × height (cm) ÷ serum creatinine (mg/dL)

Creatinine in µmol/L is divided by 88.4 to give mg/dL.
Creatinine must be measured with an enzymatic, IDMS-traceable method.

The principle

Creatinine comes from muscle and is cleared mainly by filtration in the kidneys, so lower filtration means higher blood creatinine. In children, muscle mass grows roughly with height, so height stands in for creatinine production. Dividing height by creatinine therefore tracks filtration, and the constant 0.413 was fitted in the CKiD study of children with chronic kidney disease against measured GFR. Older equations with a constant of 0.55 were built for the older Jaffe test and overestimate GFR with today's assays.

Worked example

Default inputs: age 8, height 128 cm, creatinine 0.5 mg/dL.

Creatinine in µmol/L = 0.5 × 88.4 = 44.
Height ÷ creatinine = 128 ÷ 0.5 = 256.
eGFR = 0.413 × 256 = 105.7 mL/min/1.73 m².

Each point is the calculator re-run with only “Serum creatinine” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Serum creatinine	Estimated GFR (mL/min/1.73 m²)
0.125	422.9
0.25	211.5
0.375	141
0.5	105.7
0.625	84.6
0.75	70.5
1	52.9

How to read the result

Where does your result fall?

A GFR of about 90 or more is usually considered normal after early childhood; values below 60 for three months or more indicate chronic kidney disease. Infants under 2 years naturally have lower GFR. The estimate is less reliable in very muscular or very thin children, in babies under 1 year and when kidney function is changing quickly.

Common mistakes

Using the old 0.55 constant with an enzymatic creatinine.
Entering creatinine in µmol/L while the unit is set to mg/dL.
Using a height measured months ago in a fast-growing child.

Keep in mind: This is not a diagnosis. Kidney function in children should be interpreted by a doctor, often with repeat tests.

Frequently asked questions

What is a normal GFR for a child?

Usually about 90 mL/min/1.73 m² or more after the first two years.

Why is height used instead of weight?

Height relates more closely to muscle mass, which drives creatinine production.

Is there a newer equation?

Yes, equations combining creatinine with cystatin C are more accurate, but the bedside formula is widely used.

Sources: Schwartz GJ, Muñoz A, Schneider MF, et al., "New equations to estimate GFR in children with CKD", J Am Soc Nephrol 2009;20(3):629–637

Checked 9 Nov 2026. Schwartz GJ, Muñoz A, Schneider MF, et al., “New equations to estimate GFR in children with CKD”, J Am Soc Nephrol 2009 (bedside formula 0.413 × height/serum creatinine; CKiD cohort; enzymatic creatinine).

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