Dosage Calculator
Calculate the precise amount of medication to administer based on the prescribed dose and available concentration.
Result:
Understanding Dosage Calculations: A Critical Skill
Dosage calculation is a fundamental skill in healthcare, ensuring patients receive the correct amount of medication. Administering an incorrect dose can have serious, even life-threatening, consequences. This calculator helps simplify the most common dosage calculation scenario: determining the volume or number of units to administer based on a prescribed dose and the available medication concentration.
The Basic Dosage Calculation Formula
The most frequently used formula for calculating medication dosages is often referred to as "Desired over Have" or "D/H x Q". It helps determine the quantity (Q) to administer when you know the desired dose (D) and what you have on hand (H).
The formula is:
Administer Volume/Units = (Prescribed Dose / Available Amount) × Available Volume/Unit
- Prescribed Dose: This is the amount of medication the doctor has ordered for the patient. It's what you want to give. (e.g., 250 mg)
- Available Amount: This is the amount of medication contained within the available stock. It's what you have in your supply. (e.g., 125 mg)
- Available Volume/Unit: This is the volume (for liquids) or the number of units (for tablets/capsules) that contains the 'Available Amount'. (e.g., 5 mL, 1 tablet)
How the Calculator Works
Our dosage calculator uses this precise formula. You simply input:
- The Prescribed Dose (e.g., 250 mg).
- The Available Amount (e.g., 125 mg).
- The Available Volume/Unit (e.g., 5 mL).
The calculator then performs the calculation: (250 mg / 125 mg) × 5 mL = 10 mL. This means you would administer 10 mL of the medication.
Example Scenarios:
Example 1: Liquid Medication
A doctor prescribes 500 mg of Amoxicillin. You have Amoxicillin suspension available as 250 mg per 5 mL.
- Prescribed Dose: 500 mg
- Available Amount: 250 mg
- Available Volume/Unit: 5 mL
Using the calculator:
(500 mg / 250 mg) × 5 mL = 10 mL
You would administer 10 mL of Amoxicillin.
Example 2: Tablet Medication
A patient needs 0.5 mg of a medication. The available tablets are 0.25 mg per tablet.
- Prescribed Dose: 0.5 mg
- Available Amount: 0.25 mg
- Available Volume/Unit: 1 tablet
Using the calculator:
(0.5 mg / 0.25 mg) × 1 tablet = 2 tablets
You would administer 2 tablets.
Importance of Accuracy
Even small errors in dosage calculations can lead to significant patient harm. Always double-check your calculations, especially for high-alert medications. If you are unsure, consult with a colleague or pharmacist. This calculator is a tool to assist, but it does not replace professional judgment and verification.