Liquid Chlorine Calculator

Liquid Chlorine Calculator

Calculate the exact amount of liquid chlorine needed to reach your target sanitization levels.

5.25% (Household Bleach) 6.0% 8.25% 10% (Pool Grade) 12.5% (Professional Grade) 15%

Required Dosage

How to Use the Liquid Chlorine Calculator

Maintaining the proper Free Chlorine (FC) level is essential for keeping your swimming pool safe, clear, and free of algae. Liquid chlorine (sodium hypochlorite) is one of the most popular methods for sanitizing pools because it doesn't add Cyanuric Acid (stabilizer) or Calcium to the water.

The Math Behind Chlorine Dosage

This calculator uses the standard chemical formula for liquid chlorine concentration. To calculate the dosage, we determine the "ppm-gallons" required. For example, 12.8 fluid ounces of 10% liquid chlorine will raise 10,000 gallons of water by exactly 1.0 ppm.

Step-by-Step Guide

  1. Test Your Water: Use a high-quality drop test kit to determine your current Free Chlorine level in parts per million (ppm).
  2. Know Your Volume: You must have an accurate estimate of your pool's total gallon capacity.
  3. Identify Strength: Check the label on your chlorine jug. Most "pool store" chlorine is 10% or 12.5%, while grocery store bleach is typically 5.25% to 6%.
  4. Calculate and Add: Enter your numbers above. When adding chlorine, pour it slowly in front of a return jet while the pump is running to ensure proper mixing.

Practical Example

Suppose you have a 20,000-gallon pool. Your current chlorine level is 1.0 ppm, and you want to reach 5.0 ppm (a 4.0 ppm increase). You are using 12.5% professional strength liquid chlorine.

  • Target Increase: 4 ppm
  • Calculation: (20,000 / 12,800) * (4 / 0.125)
  • Result: Approximately 82 fluid ounces (about 10.2 cups or 0.64 gallons).
Pro Tip: Always add chlorine at dusk or night. Sunlight degrades chlorine rapidly (UV rays break down the HOCl molecule), so adding it after the sun goes down allows the chemical to work effectively overnight.
function calculateLiquidChlorine() { var volume = parseFloat(document.getElementById('poolVolume').value); var strength = parseFloat(document.getElementById('chlorineStrength').value); var current = parseFloat(document.getElementById('currentFC').value); var target = parseFloat(document.getElementById('targetFC').value); var resultDiv = document.getElementById('chlorineResult'); var ouncesOutput = document.getElementById('finalOunces'); var cupsOutput = document.getElementById('finalCups'); var gallonsOutput = document.getElementById('finalGallons'); if (isNaN(volume) || isNaN(current) || isNaN(target) || volume <= 0) { alert("Please enter valid numbers for volume and chlorine levels."); return; } var delta = target – current; if (delta = 1) { gallonsOutput.innerHTML = "(" + (Math.round(neededGallons * 100) / 100) + " Gallons)"; } else if (neededGallons >= 0.25) { gallonsOutput.innerHTML = "(" + (Math.round(neededGallons * 4) / 4) + " Gallons)"; } else { gallonsOutput.innerHTML = ""; } resultDiv.style.display = 'block'; resultDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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