Use the West nomogram by drawing a straight line between the height and weight of a child. This line crosses the surface area column and gives an estimation of the body surface area for this child, according to RMIT University, but it is only effective if the child is of normal height and weight. The West nomogram is a physical representation of the Du Bois & Du Bois body surface area formula, according to Chegg.
The West nomogram allows users to calculate the dosage of medicines that they can give to children based suggested adult dosages, according to Easy Calculation. However, weight has more influence on the dose that should be given to a child than any other factor when calculating pediatric doses, as explained by Medical Office Pharmacology.
Do not use the West nomogram when calculating doses for pediatric patients of abnormal height or weight, toddlers, newborns, and older children, according to Medical Office Pharmacology. Calculations for toddlers should use Fried's Rule, and dosage calculations for older children require the use of Youngs Rule.
Calculate a child pediatric dose using the West nomogram rule with an online calculator such as the one available at EasyCalculation.com as of 2015. This tool uses the child's body surface area and the typical adult dose to provide an estimated child's dose give in milligram units.