Paediatric Weight & BSA Estimator

This app estimates a child's body weight and body surface area (BSA) from a length measurement and body habitus, or estimates BSA from a known weight. It is based on the Tamale formulas (Yakubu, Coulthard & Wells) and Boyd's BSA equation.

For clinical use as an aid only. If an accurate scale is available, a measured weight should always be preferred over an estimate. Not validated for children under 1 month, or for lengths outside 45–180 cm.

Step 1 of 4 — Age group

Choose the age range that best matches the child, to show the most appropriate reference pictures.

Step 2 of 4 — Hair and skin tone

Choose the reference pictures that best match the child's hair and skin tone.

Step 3 of 4 — Body habitus

Compare the child (front and side view) to the pictures below, from 1 (very thin) to 7 (very obese), and choose the closest match.

Hard to see the detail? Tap the picture to view it full-screen, where you can pinch to zoom in.

Step 4 of 4 — Length

Estimate BSA from a known weight