Please enter valid positive numbers for all fields.
Weight in kg:0.000 kg
Total Active Drug Required:0.00 mg
Volume to Administer:0.00 mL
(Equivalent in microliters):0 µL
Understanding the Dose Calculation Formula for Rats
Accurate dosing is critical in veterinary science and pharmacological research involving laboratory rats. Administering the correct volume ensures data integrity and animal welfare. The calculator above utilizes standard pharmacological formulas to convert weight, dosage, and concentration into a specific administration volume.
The Formula
To calculate the injection volume, you must determine the total amount of drug required for the specific animal and divide it by the concentration of your solution.
Convert Weight: Since rats are small, their weight is usually measured in grams. This must be converted to kilograms (Divide grams by 1000).
Calculate Total Drug Amount: Multiply Weight (kg) by the Target Dosage (mg/kg) to get the milligrams of drug needed.
Calculate Volume: Divide the milligrams needed by the Stock Concentration (mg/mL) to get the volume in milliliters.
Example Calculation
Let's say you have a laboratory rat and a prepared drug solution with the following parameters:
Rat Weight: 300 grams
Target Dosage: 20 mg/kg
Stock Concentration: 10 mg/mL
Step 1: Convert weight to kg.
300 g ÷ 1000 = 0.3 kg
Step 2: Calculate total drug needed.
0.3 kg × 20 mg/kg = 6 mg
Step 3: Calculate volume to inject.
6 mg ÷ 10 mg/mL = 0.6 mL
Common Administration Routes for Rats
The calculated volume must be suitable for the route of administration. Recommended maximum volumes for an adult rat (approx. 250g-300g) typically include:
Intraperitoneal (IP): 5 – 10 mL/kg (approx. 1-2 mL total)
Subcutaneous (SC): 5 – 10 mL/kg (approx. 1-2 mL total)
Intravenous (IV): 5 mL/kg (bolus)
Oral Gavage (PO): 10 mL/kg (approx. 2-3 mL total)
Note: Always consult your institutional Animal Care and Use Committee (IACUC) guidelines for specific volume limits.
function calculateRatDose() {
// Get input values
var weightG = document.getElementById('ratWeight').value;
var doseMgKg = document.getElementById('targetDose').value;
var concMgMl = document.getElementById('stockConc').value;
var errorDiv = document.getElementById('errorMsg');
var resultBox = document.getElementById('resultBox');
// Reset display
errorDiv.style.display = 'none';
resultBox.style.display = 'none';
// Validation logic
if (weightG === "" || doseMgKg === "" || concMgMl === "") {
errorDiv.innerText = "Please fill in all fields.";
errorDiv.style.display = 'block';
return;
}
var w = parseFloat(weightG);
var d = parseFloat(doseMgKg);
var c = parseFloat(concMgMl);
if (isNaN(w) || isNaN(d) || isNaN(c) || w <= 0 || d < 0 || c <= 0) {
errorDiv.innerText = "Please enter valid positive numbers.";
errorDiv.style.display = 'block';
return;
}
// Calculation Logic
// 1. Convert grams to kg
var weightKg = w / 1000;
// 2. Calculate Total Drug in mg
var totalDrugMg = weightKg * d;
// 3. Calculate Volume in mL
var volumeMl = totalDrugMg / c;
// 4. Calculate Microliters (mL * 1000) for precision reference
var volumeUl = volumeMl * 1000;
// Update UI
document.getElementById('resWeightKg').innerText = weightKg.toFixed(3) + " kg";
document.getElementById('resTotalDrug').innerText = totalDrugMg.toFixed(3) + " mg";
// Dynamic formatting for volume based on size
var volumeDisplay = volumeMl < 0.01 ? volumeMl.toExponential(3) : volumeMl.toFixed(3);
document.getElementById('resVolume').innerText = volumeDisplay + " mL";
document.getElementById('resVolumeUl').innerText = volumeUl.toFixed(1) + " µL";
// Show results
resultBox.style.display = 'block';
}