Accurate Medication Dosage Calculation for Healthcare Professionals
Medication Dosage Calculator
Enter patient's weight in kilograms (kg).
Enter the concentration of the drug (e.g., mg/mL).
Enter the desired dose per unit of weight (e.g., mg/kg).
mg
mcg
mL
Select the unit for the desired dose.
mg/mL
mcg/mL
units/mL
Select the unit for the drug concentration.
Calculation Results
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—
—
—
Formula Used:
1. Calculate the total amount of drug needed: Total Drug Amount = Patient Weight (kg) * Desired Dose (per kg)
2. Calculate the volume to administer: Total Volume = Total Drug Amount / Drug Concentration (ensure units are compatible, e.g., mg / (mg/mL) = mL)
Dosage Calculation Data Table
Medication Dosage Parameters
Parameter
Input Value
Unit
Patient Weight
—
kg
Drug Concentration
—
—
Desired Dose
—
—
Calculated Total Drug Amount
—
mg (or mcg)
Calculated Volume to Administer
—
mL
Dosage vs. Volume Relationship
Visualizing how changes in desired dose affect the volume to administer, given fixed patient weight and drug concentration.
What is a Med Dosage Calculator?
A Med Dosage Calculator is a specialized tool designed to assist healthcare professionals, pharmacists, and sometimes patients in accurately determining the correct amount of medication to administer. In the field of medicine, precision is paramount. Even small errors in dosage can lead to under-treatment, over-treatment, adverse drug reactions, or treatment failure. This calculator simplifies the complex calculations often required, especially when dealing with weight-based dosing, varying drug concentrations, and different units of measurement. It acts as a crucial safety net, helping to ensure patient safety and therapeutic efficacy. The primary goal of a med dosage calculator is to translate a prescribed dose into a measurable volume or quantity of medication that can be safely given to a patient.
Who Should Use It:
Nurses (in hospitals, clinics, and home care)
Physicians and Medical Assistants
Pharmacists and Pharmacy Technicians
Paramedics and Emergency Medical Technicians (EMTs)
Medical Students and Residents
Caregivers administering medication under professional guidance
Common Misconceptions:
"It replaces clinical judgment": While invaluable, the calculator is a tool. Clinical assessment of the patient's condition, allergies, and other medications remains critical.
"All calculators are the same": Different calculators may handle different units, specific drug classes, or complex dosing regimens. Always ensure the calculator is appropriate for the task.
"It's only for emergencies": Med dosage calculators are used daily for routine medication administration across various healthcare settings.
"It's foolproof": Input errors can still lead to incorrect results. Double-checking inputs and understanding the underlying principles are essential.
Med Dosage Calculator Formula and Mathematical Explanation
The core of a med dosage calculator relies on a straightforward, yet critical, set of formulas derived from basic dimensional analysis and the principles of drug administration. The most common scenario involves calculating the volume of a liquid medication to administer based on the patient's weight, the prescribed dose per unit of weight, and the concentration of the available medication.
Step-by-Step Derivation:
Determine the Total Drug Amount Required: This is typically calculated by multiplying the patient's weight by the prescribed dose per unit of weight. For example, if a drug is prescribed at 2 mg/kg and the patient weighs 70 kg, the total drug amount needed is 2 mg/kg * 70 kg = 140 mg.
Determine the Volume to Administer: Once the total drug amount is known, you need to figure out how much of the liquid medication contains that amount. This is done by dividing the total drug amount by the concentration of the medication. If the available medication has a concentration of 50 mg/mL, and you need 140 mg, the volume to administer is 140 mg / (50 mg/mL) = 2.8 mL.
Variable Explanations:
Understanding the variables is key to using the calculator correctly:
Patient Weight: The mass of the patient, usually measured in kilograms (kg) for pediatric and adult dosing.
Desired Dose: The prescribed amount of active drug substance the patient should receive, often expressed per unit of body weight (e.g., mg/kg, mcg/kg).
Drug Concentration: The amount of active drug substance present in a specific volume of the liquid medication, typically expressed as mg/mL, mcg/mL, or units/mL.
Total Drug Amount: The absolute quantity of the active drug substance required for the patient, calculated based on weight and desired dose.
Total Volume to Administer: The final calculated volume of the liquid medication that needs to be drawn up and given to the patient.
Variables Table:
Medication Dosage Calculation Variables
Variable
Meaning
Unit
Typical Range
Patient Weight
Mass of the patient
kg
0.5 kg – 200 kg
Desired Dose
Prescribed drug amount per unit of weight
mg/kg, mcg/kg, etc.
0.01 – 50 (highly variable by drug)
Drug Concentration
Amount of drug in a given volume
mg/mL, mcg/mL, units/mL
0.1 – 1000 (highly variable by drug)
Total Drug Amount
Total active drug needed
mg, mcg, units
Calculated (e.g., 1 mg – 10,000 mg)
Total Volume to Administer
Volume of liquid medication to give
mL
Calculated (e.g., 0.1 mL – 50 mL)
Practical Examples (Real-World Use Cases)
Example 1: Pediatric Antibiotic Dosing
A pediatrician prescribes Amoxicillin suspension for a child weighing 15 kg. The prescribed dose is 25 mg/kg/day, divided into two doses. The available Amoxicillin suspension has a concentration of 125 mg/5 mL.
Patient Weight: 15 kg
Desired Dose: 25 mg/kg
Drug Concentration: 125 mg / 5 mL (which is 25 mg/mL)
Calculation Steps:
Total Drug Amount per dose: 15 kg * 25 mg/kg = 375 mg
Volume to Administer per dose: 375 mg / (25 mg/mL) = 15 mL
Result Interpretation: The nurse needs to administer 15 mL of the Amoxicillin suspension to the child for each dose. Since the daily dose is divided, this 15 mL would be given twice a day.
Example 2: Critical Care Medication Dosing
A patient in the ICU requires a continuous infusion of a vasopressor. The physician orders Dopamine at 5 mcg/kg/min. The patient weighs 80 kg. The pharmacy prepares a bag containing 400 mg of Dopamine in 250 mL of Normal Saline.
Patient Weight: 80 kg
Desired Dose: 5 mcg/kg/min
Drug Concentration: 400 mg / 250 mL = 1.6 mg/mL. We need this in mcg/mL: 1.6 mg/mL * 1000 mcg/mg = 1600 mcg/mL.
Calculation Steps:
Total Drug Amount per minute: 80 kg * 5 mcg/kg/min = 400 mcg/min
Volume to Administer per minute: 400 mcg/min / (1600 mcg/mL) = 0.25 mL/min
Result Interpretation: The infusion pump should be set to deliver 0.25 mL per minute to achieve the desired therapeutic effect. This highlights the need for precise calculations in critical care settings, often managed by infusion pumps.
How to Use This Med Dosage Calculator
Using this Med Dosage Calculator is designed to be intuitive and efficient. Follow these steps to ensure accurate calculations:
Step-by-Step Instructions:
Input Patient Weight: Enter the patient's weight in kilograms (kg) into the "Patient Weight" field. Ensure accuracy, as this is a primary factor in weight-based dosing.
Input Drug Concentration: Enter the concentration of the medication as provided on the vial or packaging. Select the correct units (e.g., mg/mL, mcg/mL) from the dropdown menus.
Input Desired Dose: Enter the prescribed dose, typically specified per kilogram of body weight (e.g., 10 mg/kg). Select the appropriate unit (mg, mcg) for the dose itself.
Select Units: Ensure you have selected the correct units for both "Dose Unit" and "Concentration Unit" to match the medication's labeling and the prescription.
Click "Calculate Dosage": Once all fields are populated accurately, click the "Calculate Dosage" button.
Review Results: The calculator will display the "Total Volume to Administer" (the primary result), along with intermediate values like "Total Drug Amount" and "Dose per kg".
Verify with Table: Check the "Dosage Calculation Data Table" for a clear summary of all inputs and calculated outputs, which can help in cross-referencing.
Use the Chart: The dynamic chart provides a visual representation of how dosage changes might affect the volume, useful for understanding dose-response relationships.
How to Read Results:
Total Volume to Administer: This is the most critical output. It tells you exactly how many milliliters (mL) of the medication solution you need to measure and give to the patient.
Total Drug Amount: This shows the total quantity of the active pharmaceutical ingredient (API) the patient will receive based on the calculation.
Dose per kg / Concentration: These intermediate values help confirm the calculation logic and provide context.
Decision-Making Guidance:
Always cross-reference the calculated volume with the patient's prescription and the medication's administration guidelines. If the calculated volume seems unusually high or low, or if you have any doubts, consult with a pharmacist or senior clinician before administering the medication. This calculator is a tool to aid, not replace, professional judgment and established protocols. For continuous infusions, the "Total Volume to Administer" often represents the volume per hour or per minute, depending on how the calculator is configured or the context of the prescription.
Key Factors That Affect Med Dosage Results
Several factors can influence the accuracy and appropriateness of medication dosages, even when using a calculator. Understanding these is crucial for safe medication administration:
Patient Weight and Body Surface Area (BSA): While this calculator primarily uses weight, some medications, particularly chemotherapy agents, are dosed based on BSA. BSA calculations are more complex and require height as well. Using the wrong metric can lead to significant dosing errors.
Age and Organ Function: Infants, children, and the elderly often metabolize drugs differently than adults. Impaired kidney or liver function can significantly reduce a drug's clearance from the body, necessitating dose adjustments to prevent toxicity. This calculator does not account for these physiological differences.
Drug Formulation and Concentration: Medications come in various strengths and forms (e.g., tablets, capsules, oral solutions, injectables). Always verify the concentration of the specific product you are using. A change in formulation or concentration requires recalculation. For example, switching from a 100 mg/mL injectable to a 50 mg/mL injectable will double the volume needed for the same dose.
Route of Administration: The bioavailability (the fraction of an administered dose of unchanged drug that reaches systemic circulation) varies significantly by route. An oral dose might be much higher than an intravenous (IV) dose of the same drug because oral medications undergo first-pass metabolism in the liver.
Specific Drug Properties: Some drugs have a narrow therapeutic index, meaning the difference between an effective dose and a toxic dose is small. These require extremely careful calculation and monitoring. Others may require loading doses followed by maintenance doses.
Patient Compliance and Adherence: For outpatient medications, whether the patient takes the medication as prescribed significantly impacts the outcome. This calculator assumes perfect adherence to the calculated dose.
Drug Interactions: Other medications a patient is taking can affect the metabolism or excretion of the drug being calculated, potentially altering its required dose or increasing the risk of side effects.
Disease State and Severity: The severity of an illness or the presence of specific complications can influence drug requirements. For instance, a patient with severe dehydration might require different fluid and electrolyte management, which could indirectly affect drug distribution and dosing.
Frequently Asked Questions (FAQ)
What is the difference between desired dose and drug concentration?
The desired dose is what the doctor wants the patient to receive (e.g., 10 mg/kg). The drug concentration is how the medication is supplied (e.g., 50 mg/mL). You use both to figure out how much liquid volume to give.
Can this calculator be used for non-weight-based doses?
This specific calculator is primarily designed for weight-based dosing. For fixed doses (e.g., 500 mg regardless of weight), you would calculate the volume directly: Volume = Fixed Dose / Concentration. However, you can input a desired dose per kg that is effectively a fixed dose if the weight input is ignored or set to 1kg for calculation purposes, but it's less direct.
What if the drug concentration is in mg/L or other units?
You must convert the concentration to the units expected by the calculator (e.g., mg/mL) before inputting it. For example, 1000 mg/L is equivalent to 1 mg/mL. Always perform necessary conversions carefully.
How accurate are these calculators?
The accuracy depends entirely on the accuracy of the input values and the correctness of the underlying formula. This calculator uses standard formulas, but input errors or using it for inappropriate situations can lead to incorrect results. Always double-check your inputs and the final result.
Should I use this calculator for chemotherapy drugs?
While the basic principle applies, chemotherapy is often dosed by Body Surface Area (BSA) and has very specific protocols. This calculator is primarily for weight-based dosing. For chemotherapy, always use specialized protocols and BSA calculators, and consult with an oncology pharmacist.
What does "Total Volume to Administer" mean?
This is the final, practical measurement. It's the volume (usually in mL) of the liquid medication you need to draw into a syringe or administer via an infusion pump to deliver the correct dose to the patient.
Can I use this for solid medications like tablets?
No, this calculator is specifically for liquid medications where you need to determine the volume to administer based on concentration. Dosing for tablets or capsules typically involves selecting the correct number of pills based on their strength (e.g., 250 mg tablets for a 500 mg dose means taking 2 tablets).
What if the calculated volume is very small (e.g., less than 0.1 mL)?
Very small volumes can be difficult to measure accurately with standard syringes. In such cases, consider using a more concentrated form of the drug if available, or using a specialized low-volume syringe (e.g., 1 mL syringe). Always consult with a pharmacist if accuracy is a concern.
How do I handle unit conversions (e.g., mg to mcg)?
You must perform necessary unit conversions before entering the values into the calculator, or ensure your selected units in the dropdowns accurately reflect the prescription and drug concentration. For example, 1 mg = 1000 mcg. If the desired dose is 500 mcg and the concentration is 1 mg/mL, convert the dose to 0.5 mg first, then calculate: 0.5 mg / (1 mg/mL) = 0.5 mL.
Related Tools and Internal Resources
Med Dosage CalculatorUse our advanced calculator for precise medication dose calculations.
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function getElement(id) {
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}
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return true;
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function calculateDosage() {
var patientWeight = parseFloat(getElement('patientWeight').value);
var drugConcentration = parseFloat(getElement('drugConcentration').value);
var desiredDose = parseFloat(getElement('desiredDose').value);
var doseUnit = getElement('doseUnit').value;
var concentrationUnit = getElement('concentrationUnit').value;
var isValid = true;
// Input validation with specific ranges
isValid &= validateInput(patientWeight, 'patientWeight', 'patientWeightError', 0.1, 500, false); // Weight between 0.1kg and 500kg
isValid &= validateInput(drugConcentration, 'drugConcentration', 'drugConcentrationError', 0.01, 10000, false); // Concentration between 0.01 and 10000
isValid &= validateInput(desiredDose, 'desiredDose', 'desiredDoseError', 0.001, 1000, false); // Desired dose between 0.001 and 1000
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// Clear results if validation fails
getElement('totalVolume').innerText = '–';
getElement('totalDrugAmount').innerText = '–';
getElement('dosePerKg').innerText = '–';
getElement('concentrationMgMl').innerText = '–';
updateTable('–', '–', '–', '–', '–');
updateChart([]); // Clear chart
return;
}
// Unit handling for concentration (e.g., mg/mL)
var concentrationMgMlValue;
var concentrationUnitLabel = concentrationUnit; // Default label
if (concentrationUnit === 'mg/mL') {
concentrationMgMlValue = drugConcentration;
} else if (concentrationUnit === 'mcg/mL') {
concentrationMgMlValue = drugConcentration / 1000; // Convert mcg/mL to mg/mL
concentrationUnitLabel = 'mcg/mL';
} else if (concentrationUnit === 'units/mL') {
// For units/mL, we can't directly convert to mg/mL without a conversion factor.
// We'll display the input value and unit, and calculate volume based on it.
concentrationMgMlValue = drugConcentration; // Use the raw value for calculation
concentrationUnitLabel = 'units/mL';
} else {
// Fallback for unexpected units, though select options limit this
concentrationMgMlValue = drugConcentration;
}
// Unit handling for desired dose (e.g., mg/kg)
var desiredDoseValue = desiredDose;
var doseUnitLabel = doseUnit; // Default label
if (doseUnit === 'mcg') {
desiredDoseValue = desiredDose / 1000; // Convert mcg to mg for calculation consistency
doseUnitLabel = 'mcg/kg';
} else if (doseUnit === 'mL') {
// This case implies the desired dose is already a volume, which is unusual for mg/kg type calculations.
// Assuming it might be a direct volume prescription per kg, e.g., 0.5 mL/kg.
// For this calculator's primary logic (mg/kg), this might need adjustment or clarification.
// Let's assume for now it's a direct volume per kg.
desiredDoseValue = desiredDose; // Keep as is, but label will reflect mL/kg
doseUnitLabel = 'mL/kg';
} else { // mg
doseUnitLabel = 'mg/kg';
}
// Calculations
var totalDrugAmount = patientWeight * desiredDoseValue; // This will be in mg if doseUnit was mg or mcg converted to mg
var totalVolume;
if (concentrationUnit === 'units/mL') {
// If concentration is in units/mL, totalDrugAmount should ideally be in units.
// This scenario requires careful handling. If desired dose was mg/kg, and concentration is units/mL,
// there's a unit mismatch. For simplicity here, we'll assume if concentration is units/mL,
// the desired dose should also be in compatible units (e.g., units/kg).
// If desiredDoseValue was converted from mcg to mg, this logic needs refinement.
// Let's recalculate totalDrugAmount assuming desiredDoseValue is now in the correct base unit (e.g., mg or units)
// and concentrationMgMlValue is the numerical value from the input.
// Re-evaluate based on selected units:
var effectiveDesiredDoseValue = desiredDose;
var effectiveDesiredDoseUnit = doseUnit;
var effectiveConcentrationValue = drugConcentration;
var effectiveConcentrationUnit = concentrationUnit;
// Standard calculation: Total Drug Amount = Weight * Dose per Weight
// Then: Volume = Total Drug Amount / Concentration
// We need to ensure units align. Let's assume the calculator aims for mg and mL.
var totalDrugAmountMg = 0;
if (doseUnit === 'mg') {
totalDrugAmountMg = patientWeight * desiredDose;
} else if (doseUnit === 'mcg') {
totalDrugAmountMg = patientWeight * (desiredDose / 1000);
} else if (doseUnit === 'mL') {
// This implies a direct volume/kg prescription.
// We'll calculate the total volume directly.
// totalVolume = patientWeight * desiredDose; // This would be mL/kg * kg = mL
// However, the calculator structure implies calculating volume FROM drug amount.
// Let's stick to the standard path and flag this as potentially needing specific handling.
// For now, we'll treat it as if the desired dose implies a mg/kg equivalent if possible, or flag it.
// A safer approach is to require mg/kg or mcg/kg for this calculator's core logic.
// Let's assume 'mL' as a dose unit is an error for this calculator's primary function.
// We'll proceed assuming mg or mcg.
alert("Warning: 'mL' as a desired dose unit per kg is ambiguous for this calculator. Please use mg/kg or mcg/kg.");
return; // Stop calculation if ambiguous unit is selected
}
var concentrationValueMgMl = 0;
if (concentrationUnit === 'mg/mL') {
concentrationValueMgMl = drugConcentration;
} else if (concentrationUnit === 'mcg/mL') {
concentrationValueMgMl = drugConcentration / 1000;
} else if (concentrationUnit === 'units/mL') {
// Cannot directly calculate volume in mL if concentration is in units/mL and dose is mg/kg.
// This requires a conversion factor specific to the drug (e.g., 1 unit = X mg).
// For this generic calculator, we cannot proceed reliably.
alert("Error: Cannot calculate volume when drug concentration is in 'units/mL' and desired dose is in 'mg/kg' or 'mcg/kg' without a specific drug conversion factor.");
return; // Stop calculation
}
if (concentrationValueMgMl === 0) {
alert("Error: Invalid drug concentration value for calculation.");
return;
}
totalVolume = totalDrugAmountMg / concentrationValueMgMl;
} else {
// Standard calculation path (mg/kg dose, mg/mL concentration)
totalDrugAmount = patientWeight * desiredDoseValue; // Assuming desiredDoseValue is in mg/kg
totalVolume = totalDrugAmount / concentrationMgMlValue; // Assuming concentrationMgMlValue is in mg/mL
}
// Format results
var formattedTotalVolume = totalVolume.toFixed(2); // e.g., 2 decimal places for mL
var formattedTotalDrugAmount = totalDrugAmount.toFixed(2); // e.g., 2 decimal places for mg
var formattedDosePerKg = desiredDose.toFixed(2) + ' ' + doseUnitLabel.split('/')[0]; // Show original dose unit part
var formattedConcentrationMgMl = concentrationMgMlValue.toFixed(2) + ' mg/mL'; // Always show as mg/mL
// Display results
getElement('totalVolume').innerText = formattedTotalVolume + ' mL';
getElement('totalDrugAmount').innerText = formattedTotalDrugAmount + ' mg'; // Assuming mg is the base unit
getElement('dosePerKg').innerText = formattedDosePerKg;
getElement('concentrationMgMl').innerText = formattedConcentrationMgMl;
// Update table
updateTable(
patientWeight.toFixed(2),
drugConcentration.toFixed(2),
concentrationUnit,
desiredDose.toFixed(2),
doseUnit,
formattedTotalDrugAmount + ' mg', // Assuming mg
formattedTotalVolume + ' mL'
);
// Update chart
updateChart({
patientWeight: patientWeight,
drugConcentration: drugConcentration, // Use original input value for chart context
concentrationUnit: concentrationUnit,
desiredDose: desiredDose,
doseUnit: doseUnit
});
}
function updateTable(patientWeight, drugConcentration, concentrationUnit, desiredDose, doseUnit, totalDrugAmount, totalVolume) {
getElement('tablePatientWeight').innerText = patientWeight;
getElement('tableDrugConcentration').innerText = drugConcentration;
getElement('tableConcentrationUnit').innerText = concentrationUnit;
getElement('tableDesiredDose').innerText = desiredDose;
getElement('tableDoseUnit').innerText = doseUnit;
getElement('tableTotalDrugAmount').innerText = totalDrugAmount;
getElement('tableTotalVolume').innerText = totalVolume;
}
function updateChart(inputs) {
var ctx = getElement('dosageChart').getContext('2d');
// Clear previous chart if it exists
if (chartInstance) {
chartInstance.destroy();
}
if (!inputs || Object.keys(inputs).length === 0) {
// If no inputs provided (e.g., on reset or initial load), don't draw chart or draw empty
// For now, let's just not draw if inputs are empty.
return;
}
var patientWeight = inputs.patientWeight || 70; // Default if not provided
var drugConcentration = inputs.drugConcentration || 50; // Default
var concentrationUnit = inputs.concentrationUnit || 'mg/mL';
var desiredDoseBase = inputs.desiredDose || 10; // Base dose for chart variation
var doseUnit = inputs.doseUnit || 'mg';
var chartData = {
labels: [],
datasets: [{
label: 'Total Volume (mL)',
data: [],
borderColor: 'rgb(0, 74, 153)',
backgroundColor: 'rgba(0, 74, 153, 0.2)',
fill: false,
tension: 0.1
},
{
label: 'Total Drug Amount (mg)',
data: [],
borderColor: 'rgb(40, 167, 69)',
backgroundColor: 'rgba(40, 167, 69, 0.2)',
fill: false,
tension: 0.1
}]
};
// Generate data points for the chart
// Vary the desired dose around the base input value
var doseSteps = 5;
var doseVariation = desiredDoseBase * 0.5; // Vary by 50% of the base dose
for (var i = 0; i <= doseSteps; i++) {
var currentDesiredDose = desiredDoseBase – doseVariation + (i * (2 * doseVariation / doseSteps));
if (currentDesiredDose 0) {
totalVolume = totalDrugAmountMg / concentrationValueMgMl;
}
chartData.labels.push(currentDesiredDose.toFixed(1) + ' ' + doseUnitLabelPart); // Label with dose value and unit part
chartData.datasets[0].data.push(parseFloat(totalVolume.toFixed(2)));
chartData.datasets[1].data.push(parseFloat(totalDrugAmountMg.toFixed(2)));
}
// Ensure we have data before creating the chart
if (chartData.labels.length === 0) {
return; // Don't draw if no valid data points generated
}
var chartOptions = {
responsive: true,
maintainAspectRatio: false, // Allows custom height
scales: {
y: {
beginAtZero: true,
title: {
display: true,
text: 'Amount / Volume'
}
},
x: {
title: {
display: true,
text: 'Desired Dose (' + doseUnit + '/kg)'
}
}
},
plugins: {
tooltip: {
mode: 'index',
intersect: false,
},
legend: {
position: 'top',
}
}
};
var chartConfig = {
type: 'line',
data: chartData,
options: chartOptions
};
// Create the chart
chartInstance = new Chart(ctx, chartConfig);
}
function resetCalculator() {
getElement('patientWeight').value = '70';
getElement('drugConcentration').value = '50';
getElement('desiredDose').value = '10';
getElement('doseUnit').value = 'mg';
getElement('concentrationUnit').value = 'mg/mL';
// Clear errors
getElement('patientWeightError').innerText = ";
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getElement('drugConcentrationError').innerText = ";
getElement('drugConcentrationError').classList.remove('visible');
getElement('desiredDoseError').innerText = ";
getElement('desiredDoseError').classList.remove('visible');
// Clear results
getElement('totalVolume').innerText = '–';
getElement('totalDrugAmount').innerText = '–';
getElement('dosePerKg').innerText = '–';
getElement('concentrationMgMl').innerText = '–';
// Clear table
updateTable('–', '–', '–', '–', '–', '–', '–');
// Clear chart
if (chartInstance) {
chartInstance.destroy();
chartInstance = null;
}
// Optionally redraw chart with default values or clear it
updateChart({}); // Pass empty object to clear/reset chart
}
function copyResults() {
var totalVolume = getElement('totalVolume').innerText;
var totalDrugAmount = getElement('totalDrugAmount').innerText;
var dosePerKg = getElement('dosePerKg').innerText;
var concentrationMgMl = getElement('concentrationMgMl').innerText;
var patientWeightInput = getElement('patientWeight').value;
var drugConcentrationInput = getElement('drugConcentration').value;
var concentrationUnitInput = getElement('concentrationUnit').value;
var desiredDoseInput = getElement('desiredDose').value;
var doseUnitInput = getElement('doseUnit').value;
var resultsText = "Med Dosage Calculator Results:\n\n";
resultsText += "—————————————-\n";
resultsText += "Inputs:\n";
resultsText += "—————————————-\n";
resultsText += "Patient Weight: " + patientWeightInput + " kg\n";
resultsText += "Drug Concentration: " + drugConcentrationInput + " " + concentrationUnitInput + "\n";
resultsText += "Desired Dose: " + desiredDoseInput + " " + doseUnitInput + "/kg\n";
resultsText += "\n";
resultsText += "—————————————-\n";
resultsText += "Calculated Values:\n";
resultsText += "—————————————-\n";
resultsText += "Total Volume to Administer: " + totalVolume + "\n";
resultsText += "Total Drug Amount: " + totalDrugAmount + "\n";
resultsText += "Dose per kg: " + dosePerKg + "\n";
resultsText += "Concentration (as mg/mL): " + concentrationMgMl + "\n";
// Use a temporary textarea to copy text
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try {
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// Optionally show a temporary message to the user
alert(msg);
} catch (err) {
alert('Error copying results: ' + err);
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document.body.removeChild(textArea);
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// Initial calculation and chart draw on page load
document.addEventListener('DOMContentLoaded', function() {
// Add Chart.js library dynamically if not present
if (typeof Chart === 'undefined') {
var script = document.createElement('script');
script.src = 'https://cdn.jsdelivr.net/npm/chart.js@3.7.0/dist/chart.min.js'; // Use a specific version
script.onload = function() {
// Now Chart is available, proceed with initial setup
resetCalculator(); // Set default values
calculateDosage(); // Perform initial calculation
// updateChart({}); // Ensure chart is cleared or drawn with defaults if needed
};
script.onerror = function() {
console.error("Failed to load Chart.js library.");
// Handle error: maybe disable chart functionality or show a message
};
document.head.appendChild(script);
} else {
// Chart.js is already loaded
resetCalculator(); // Set default values
calculateDosage(); // Perform initial calculation
// updateChart({}); // Ensure chart is cleared or drawn with defaults if needed
}
// Add event listeners for FAQ toggles
var faqItems = document.querySelectorAll('.faq-item .question');
faqItems.forEach(function(item) {
item.addEventListener('click', function() {
var faqItem = this.parentElement;
faqItem.classList.toggle('open');
});
});
});