Dose per kilogram × weight, then desired over have for the volume. The pound-to-kilogram step is where this one goes wrong.
mg/kg dosing
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Enter the weight and the ordered dose.
Kilograms are always the smaller number. 154 lb is 70 kg, not 339. If your dose came out far larger than you expected, check whether you multiplied by 2.2 instead of dividing.