A dilution calculator. Choose how you want to specify the dilution: by ratio (× times) or by concentration (ppm / %). In ratio mode, enter the dilution factor (for example 1000×) and the final volume you want to make, and it gives the amount of stock solution to measure, the amount of water to add, and the stock-to-water ratio. In concentration mode, enter the stock concentration (% or ppm), the target concentration and the final volume, and it solves the required stock amount, the water to add and the actual dilution factor using C1V1 = C2V2. Presets fill in both the mode and the numbers: sodium hypochlorite (chlorine bleach, ~6% stock) diluted to 200ppm for surfaces or 1000ppm for vomit/norovirus, pesticide/garden sprays at 1000× and 2000×, liquid fertilizer at 500×, and essential-oil aroma at 1%. The final volume can be entered in mL or L; amounts below 1mL are shown to 3 decimals and amounts of 1L or more also show the litre value for readability. Every calculation runs in your browser; the values you enter are never sent to any server or API. When handling products such as bleach, always follow the dilution and safety instructions on the product's own label as well.