How do you calculate a weight-based med dose (mg/kg)?

• A. Convert weight to pounds and multiply by mg/kg
• B. Convert weight to kilograms, multiply mg/kg by the patient’s weight, then round per policy and prepare the dose
• C. Use adult standard dose regardless of weight
• D. Divide weight by mg/kg

Answer: (B)

Calculating a weight-based dose uses the patient’s weight in kilograms and the prescribed amount per kilogram. First convert the weight to kilograms if needed, then multiply the dose per kilogram (mg/kg) by the patient’s weight in kilograms to obtain the total milligrams to give. Finally, round the dose according to your facility policies and prepare the amount.

Why this is correct: mg/kg is defined as milligrams per kilogram, so the total dose depends on how many kilograms the patient weighs. Multiplying by the weight in kilograms scales the dose appropriately for different sizes. Converting to kilograms ensures the units line up correctly; using pounds directly would mix units and lead to an incorrect calculation. Relying on an adult fixed dose ignores weight entirely, which can cause under- or overdosing. Dividing weight by mg/kg would invert the calculation and doesn’t yield a proper dose.