A handheld medication dosage calculator (100) and method for comparing an inputted, ordered medication dosage with a known medication dosage range in a database including an input device for inputting a desired drug name, indicating whether the drug is for a child or an adult, an amount of the drugs that are ordered, the body weight or body surface of the patient, an amount of drug available in standard packaging, and the available volume associated with the available drug and a computing mechanism for determining the dosage of the drug to be delivered. The handheld medication dosage calculator (100) provides warnings when the inputted amount of drug exceeds the dose range limits or is incorrect. The handheld medication dosage calculator (100) converts an inputted drug unit of measure into a desired unit of measure. The handheld medication dosage calculator (100) lists generic drug names, trademarked product names, drug classifications and cautionary drug warning information.