Dosage Calculation Formula Calculator
Accurate Medical Dosage for Healthcare Professionals
The dose ordered by the physician (e.g., mg, mcg, units)
The strength available (e.g., mg, mcg)
The quantity of the unit (e.g., mL, tablet, capsule)
Calculation Result:
Understanding the Dosage Calculation Formula
In clinical settings, the standard formula used for calculating medication dosages is the Desired over Have method. This ensures patient safety and accuracy when administering drugs in various forms, such as liquid, tablets, or injections.
The Universal Formula:
(D / H) × V = Y (Amount to Give)
- D (Desired): The specific dose prescribed by the doctor.
- H (Have): The strength or concentration of the drug you have in stock.
- V (Volume/Vehicle): The form the drug comes in (e.g., 1 tablet, 5 mL liquid).
- Y (Yield): The final amount to be administered to the patient.
Practical Dosage Example
Suppose a physician orders 500 mg of a medication (Desired). The pharmacy provides the medication in a concentration of 250 mg (Have) per 5 mL (Volume).
- Identify the variables: D = 500, H = 250, V = 5.
- Divide Desired by Have: 500 / 250 = 2.
- Multiply by Volume: 2 × 5 = 10.
- Result: Administer 10 mL to the patient.
Important Safety Note: Always double-check your units (mg, g, mcg) to ensure they match before calculating. If the Desired dose is in grams and the Dose on Hand is in milligrams, you must convert them to the same unit first.