Pediatrics

Pediatric Weight Estimate Calculator

Estimates a child’s weight from age when no scale or length-based tape is available.

Reviewed by Alex G, BSN, RN, CEN, CCRN, CMC, NREMT-P · From the Reference tab of the app

Turn on JavaScript to use this calculator, or open it in the web app.

Formula

Under 1 year: (months ÷ 2) + 4
1 to 5 years: (age × 2) + 8
6 to 12 years: (age × 3) + 7

How it is used

• A length-based resuscitation tape is preferred: it estimates weight from length and lists precalculated doses and equipment sizes.
• Formulas underestimate the weight of many children in developed countries; use them only when nothing better is available.

Same formula as the app. Open it in the web app.

Related one-pagers

• Pediatric Assessment and EmergenciesWeigh and record in kilograms only (Joint Commission Sentinel Event Alert 39). Without a scale, parent estimates are the most accurate, then length-based methods, with age formulas such as (age + 4) × 2 last (Young 2016). PALS 2025 notes that Broselow, PAWPER XL and Mercy tapes fall within 10–20% of measured weight and tend to underestimate total body weight while approximating ideal body weight.

Related calculators

• Pediatric Resuscitation Doses
• Pediatric Safe Dose Range
• Pediatric Vital Sign Ranges

For education and exam preparation only. Follow your institution’s protocols. For education and exam preparation only. Verify results independently and follow your institution’s protocols. Not a substitute for clinical judgment.