Body Surface Area Calculator

Calculates estimated body surface area from patient weight.

Inputs

Color mode links each input to the matching equation term and solving arithmetic.

Equation and Work

Equation:
Solving steps:
4 × kg + 7
—
numerator
kg + 90
—
denominator
BSA
—
m²
Normal/reference: Adult average BSA listed in the reference is approximately 1.7 m².

Clinical Significance

Body surface area estimates body size for hemodynamic indexing. This page uses the simplified weight-based equation; the constants 4, 7, and 90 are part of that published approximation for weight in kilograms.

BSA is used to calculate indexed values such as cardiac index and oxygen consumption index.

This weight-only equation is a simplified estimate and may differ from height-weight BSA equations.

References (APA 7th Edition)

  1. Attached equations reference supplied by the user for calculator equation confirmation.