Bleach Dilution Calculator

Use C1V1 = C2V2. Multiply your target concentration by the total batch volume you want, then divide by the stock bleach concentration to get the volume of bleach needed. For example, to make 1 liter of 0.5% sanitizer from 8.25% stock bleach: bleach volume = (0.5 x 1) / 8.25 = 0.0606 L, or about 60.6 mL, then top up with water to 1 liter total.

The CDC's general guidance for disinfecting hard, non-porous surfaces is roughly 1000 ppm available chlorine, which for 8.25% stock bleach works out to about 45.9 mL of bleach per liter of final solution (a ratio near 1:21). Always confirm the target ppm and stock strength before mixing, since bleach concentration varies by product and country.

It depends on the target strength and the stock concentration on your bottle. Enter your stock percent, choose a target percent or ppm, and set the final volume to 3.785 liters (one US gallon) in this calculator to get the exact bleach volume to add before topping up with water.

Sanitizing typically targets a lower free-chlorine level, often in the 50-200 ppm range (used for food-contact surfaces per the FDA Food Code), while disinfecting targets a higher level, commonly around 1000 ppm for general surfaces and up to 5000 ppm for cleaning up blood or other bodily fluids per CDC guidance. Always follow the specific guidance for your use case.

Multiply the percent by 10,000. For example, 8.25% sodium hypochlorite equals 82,500 ppm available chlorine as concentrated stock. When you dilute it to a target percent such as 0.1%, that corresponds to 1,000 ppm in the final solution. This calculator's ppm mode performs this conversion automatically.

Because dilution can only lower concentration, never raise it. If your requested target percent or ppm is equal to or greater than the stock bleach concentration, the calculator shows an error since no amount of dilution could reach a stronger or equal solution from a weaker stock.

Both are common. Many major brands moved to 8.25% ('Concentrated' or standard formula) for their flagship product, while some regional or store-brand bleaches remain at 5.25-6.15%. Always check the percentage printed on your specific bottle's label rather than assuming a value, since using the wrong stock percent will throw off every downstream calculation.

This calculator computes a straightforward C1V1 = C2V2 dilution and is well suited for household cleaning and sanitizing dilutions. Pool and spa chlorination involves additional factors such as chlorine demand, stabilizer levels, and water volume in cubic meters or gallons, so a dedicated pool chlorination calculator or your pool's specific dosing chart is more appropriate for that use case.

Diluted bleach solutions degrade faster than the concentrated stock, particularly when exposed to light, heat, or organic matter. Most cleaning and food-safety guidance recommends preparing a fresh diluted batch daily and discarding what remains at the end of the day rather than storing diluted solution for extended periods.

An under-strength solution may not achieve the intended sanitizing or disinfecting effect against target organisms, even though it still smells like bleach. Always calculate the correct volume for your target ppm or percent rather than estimating by eye, and consider using chlorine test strips to verify the actual concentration of a mixed batch when accuracy matters.

Always add bleach to water, not the reverse. Adding water to concentrated bleach can cause splashing and off-gassing of concentrated fumes. This calculator computes the bleach volume and the water volume separately so you can measure the water into your container first, then add the calculated bleach volume.