Bleach Dilution Calculator

Bleach dilution reduces a concentrated sodium hypochlorite product to a working concentration for an approved cleaning or disinfection task. The calculator applies the standard dilution relationship: stock concentration times stock volume equals target concentration times final volume. Solving for stock volume gives the amount of bleach to measure. Subtracting that amount from the final volume gives the approximate volume of water required. Both concentrations must use the same unit. This version accepts percent values for stock and target concentration. A target of 0.1 percent is equivalent to 1000 parts per million when the comparison is made on the same basis, because one percent equals 10,000 parts per million. Product labels may report available chlorine, sodium hypochlorite, weight percent, or another basis, and those terms are not always interchangeable. Use the concentration stated in the applicable official directions rather than guessing from a product name. Dilution arithmetic alone does not determine whether a solution is safe or effective. The required concentration and contact time depend on the organism, surface, soil load, application, and guidance from health or regulatory authorities. Household bleach also loses strength during storage, especially with heat, light, or repeated opening. A calculation based on an old nominal label concentration may overstate the strength of the prepared solution. Make fresh solution at the interval recommended by the manufacturer or relevant protocol. Bleach is corrosive and releases irritating vapors. Work with ventilation, wear protection specified by the label, avoid splashes, and use compatible containers. Add the measured bleach to water rather than pouring water into concentrated product. Never mix bleach with ammonia, acids, vinegar, alcohol, or other cleaners; hazardous gases or reactions can result. Keep chemicals away from children and do not use a food container for preparation or storage. The calculated water amount assumes that volumes are additive, which is sufficiently practical for routine aqueous bleach preparation but may not represent high-precision solution chemistry. Measure with equipment suited to the required accuracy and label the container with concentration and preparation time. This tool supports the math but does not replace the product label, a safety data sheet, workplace procedures, or public-health instructions. If those sources specify a different method, follow the authoritative instructions.