Bleach Dilution Calculator

Bleach is cheap and effective, but only at the right strength. Too weak and it does not sanitize; too strong and you are wasting product, corroding surfaces, and breathing more chlorine than you need. The right amount depends on two things: how concentrated your bleach is, and what you are trying to do with it.

Household bleach is a solution of sodium hypochlorite. Regular bleach is about 5.25 percent, while the concentrated bottles run 6 to 8.25 percent, and that difference changes the dose a lot. Strength is measured in parts per million of available chlorine once diluted. Food-contact sanitizing wants a gentle 200 ppm or so. General surface disinfecting needs more, around 600 ppm. Knocking back mold or disinfecting after illness calls for the strong stuff, roughly 2400 ppm, which is the familiar one-part-bleach-to-ten-parts-water mix.

The math is a single ratio: the volume of bleach equals your final volume times the target ppm divided by the bleach’s own ppm, where each percent of strength is 10,000 ppm. This calculator does that and then converts the answer into tablespoons, cups, or millilitres so you are not measuring bleach with a graduated cylinder.

A few rules that matter more than the numbers. Use plain unscented bleach, not the splash-less or scented kind. Mix it fresh, since a diluted solution loses strength within a day and a bottle weakens over months. Never combine bleach with ammonia or acids. And for food surfaces, follow the contact time on the label and let them air dry or rinse as directed. Enter your bleach strength, the job, and how much solution you want to make.