Leffler and Hayes developed equations for estimating the body weight of children in the Emergency Department (ED). The authors are from the University of Vermont in Burlington.

Patient selection: child in the ED <= 10 years of age


Age in Years

Weight in Kilograms

< 1 year (< 12 months)

((age in months) / 2) + 4

1 to 10 years

(2 * (age in years)) + 10



• These equations are similar to the Nelson and Best Guess equations.


The parent's estimate of weight was within 10% of the actual weight in 80% of cases while the equation was within 10% in about 50% of children.

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