Bleach, typically containing sodium hypochlorite (NaClO), is often too concentrated for direct use and needs to be diluted to achieve a safe and effective concentration for cleaning, disinfecting, or sanitizing. The calculation for dilution is based on the principle of conservation of the solute (sodium hypochlorite in this case). The amount of active ingredient remains the same before and after dilution; only the total volume changes.
The formula used is a variation of the dilution equation:
C1 * V1 = C2 * V2
Where:
C1 is the initial concentration of the stock solution (your original bleach).
V1 is the volume of the stock solution needed for the dilution.
C2 is the desired final concentration of the diluted solution.
V2 is the desired final volume of the diluted solution.
This calculator rearranges the formula to solve for V1 (the amount of stock bleach needed):
V1 = (C2 * V2) / C1
Once V1 is calculated, the amount of water needed is simply the total desired volume minus the volume of stock bleach:
Volume of Water = V2 - V1
How to Use the Calculator:
Stock Bleach Concentration: Enter the percentage of sodium hypochlorite found on your bleach bottle's label (e.g., 5.25%, 6.15%).
Desired Dilution Concentration: Enter the target percentage of sodium hypochlorite you want in your final solution (e.g., 0.5% for general disinfection, 0.1% for food surface sanitization).
Desired Final Volume: Enter the total amount of diluted solution you need (e.g., 1 Liter, 5 Liters).
The calculator will then tell you how much undiluted bleach to use and how much water to add to achieve your target.
Common Use Cases:
Household Disinfection: Diluting bleach for cleaning surfaces, floors, and bathrooms. A common target is 0.5% sodium hypochlorite.
Laundry: Adding diluted bleach to laundry for sanitization.
Food Surface Sanitization: Creating very dilute solutions (e.g., 0.1%) for sanitizing surfaces that come into contact with food.
Water Purification: In emergency situations, specific dilutions can be used to treat water.
Important Note: Always ensure you are using the correct concentration for your intended purpose. Bleach can degrade over time, so using fresh bleach is recommended. Never mix bleach with ammonia or acids, as this can create toxic gases. Always work in a well-ventilated area.
function calculateDilution() {
var stockConcentration = parseFloat(document.getElementById("stockConcentration").value);
var desiredConcentration = parseFloat(document.getElementById("desiredConcentration").value);
var desiredVolume = parseFloat(document.getElementById("desiredVolume").value);
var resultDiv = document.getElementById("result");
resultDiv.classList.remove('visible'); // Hide previous result
// Input validation
if (isNaN(stockConcentration) || stockConcentration <= 0) {
resultDiv.innerText = "Please enter a valid stock bleach concentration (greater than 0).";
resultDiv.style.backgroundColor = "#dc3545"; // Red for error
resultDiv.classList.add('visible');
return;
}
if (isNaN(desiredConcentration) || desiredConcentration < 0) {
resultDiv.innerText = "Please enter a valid desired concentration (0 or greater).";
resultDiv.style.backgroundColor = "#dc3545"; // Red for error
resultDiv.classList.add('visible');
return;
}
if (isNaN(desiredVolume) || desiredVolume = stockConcentration) {
resultDiv.innerText = "Desired concentration must be lower than stock concentration.";
resultDiv.style.backgroundColor = "#ffc107"; // Orange for warning
resultDiv.classList.add('visible');
return;
}
// Calculate V1 (volume of stock bleach)
// V1 = (C2 * V2) / C1
var volumeStockBleach = (desiredConcentration * desiredVolume) / stockConcentration;
// Calculate volume of water
// Volume of Water = V2 – V1
var volumeWater = desiredVolume – volumeStockBleach;
// Format results to a reasonable number of decimal places
var formattedVolumeStockBleach = volumeStockBleach.toFixed(2);
var formattedVolumeWater = volumeWater.toFixed(2);
var formattedDesiredVolume = desiredVolume.toFixed(2);
var formattedStockConcentration = stockConcentration.toFixed(2);
var formattedDesiredConcentration = desiredConcentration.toFixed(2);
resultDiv.innerHTML =
"To make " + formattedDesiredVolume + " Liters of a " + formattedDesiredConcentration + "% solution " +
"from " + formattedStockConcentration + "% stock bleach:" +
"Use " + formattedVolumeStockBleach + " Liters of stock bleach." +
"Add " + formattedVolumeWater + " Liters of water.";
resultDiv.style.backgroundColor = "var(–success-green)"; // Reset to green
resultDiv.classList.add('visible');
}