Easy Drug Dose Calculator
Accurate drug dosage is critical for patient safety and treatment effectiveness. This calculator helps you determine the correct volume of liquid medication to administer based on the patient's weight, the desired dose per kilogram, and the drug's concentration.
Understanding Drug Dosage
Calculating drug doses often involves a few key pieces of information:
- Patient Weight: Most pediatric and many adult drug doses are weight-based, typically expressed in kilograms (kg).
- Desired Dose (mg/kg): This is the amount of drug prescribed per kilogram of the patient's body weight. For example, 10 mg/kg means 10 milligrams of the drug for every kilogram the patient weighs.
- Drug Concentration (mg/mL): This indicates how much active drug is present in a specific volume of the medication, usually in milligrams per milliliter (mg/mL). This is crucial for liquid medications.
The goal is to determine the final volume (in mL) that needs to be administered to deliver the correct total dose (in mg) for the patient's weight.
How the Calculation Works
The calculator uses a two-step process:
- Calculate Total Milligrams (mg) Needed: Multiply the patient's weight by the desired dose per kilogram.
Total mg = Patient Weight (kg) × Desired Dose (mg/kg)
- Calculate Volume to Administer (mL): Divide the total milligrams needed by the drug's concentration.
Volume (mL) = Total mg / Drug Concentration (mg/mL)
Calculator
Example Scenario
Let's say you have a child weighing 15 kg. The doctor prescribes a medication at a dose of 10 mg/kg. The available liquid medication has a concentration of 50 mg/mL.
- Total mg needed: 15 kg × 10 mg/kg = 150 mg
- Volume to administer: 150 mg / 50 mg/mL = 3 mL
Therefore, you would administer 3 mL of the medication.
Important Disclaimer
This calculator is for educational and informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare professional before making any decisions about medication dosage or treatment. Errors in medication calculation can have serious consequences.
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function calculateDrugDose() {
var patientWeightKg = parseFloat(document.getElementById("patientWeightKg").value);
var dosePerKgMg = parseFloat(document.getElementById("dosePerKgMg").value);
var drugConcentrationMgMl = parseFloat(document.getElementById("drugConcentrationMgMl").value);
var resultDiv = document.getElementById("drugDoseResult");
// Clear previous results and error states
resultDiv.innerHTML = "";
resultDiv.classList.remove("error");
if (isNaN(patientWeightKg) || isNaN(dosePerKgMg) || isNaN(drugConcentrationMgMl) ||
patientWeightKg <= 0 || dosePerKgMg <= 0 || drugConcentrationMgMl <= 0) {
resultDiv.innerHTML = "Please enter valid, positive numbers for all fields.";
resultDiv.classList.add("error");
return;
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var totalMgNeeded = patientWeightKg * dosePerKgMg;
var volumeToAdministerMl = totalMgNeeded / drugConcentrationMgMl;
resultDiv.innerHTML = "The patient needs a total of
" + totalMgNeeded.toFixed(2) + " mg of the drug." +
"Administer
" + volumeToAdministerMl.toFixed(2) + " mL of the medication.";
}