Alcohol Dilution Calculator

Diluting alcohol relies on the conservation of absolute solute mass or volume. The core formula to find the required amount of diluent (typically water) is based on inverse proportions of the concentrations: Weak Alcohol Amount = ((Strong Alcohol Percentage - Desired Percentage) * Amount Strong Alcohol) / (Desired Percentage - Weak Alcohol Percentage). Additionally, when ethanol and water mix, molecular bonding causes a slight decrease in the total expected volume, known as volume contraction. Our calculator integrates empirical contraction algorithms to ensure your final bottled volume is exceptionally precise.

Imagine you have 750 mL of a strong spirit at 80% ABV, and you want to dilute it down to a standard 40% ABV using pure water (0% ABV). Using the dilution equation: First, find the total portions or ratio. The strong spirit portion is (40 - 0) = 40, and the water portion is (80 - 40) = 40. For 750 mL of 80% alcohol, you will need to add an equal part of water, which calculates to 750 mL of weak diluent. Factoring in a slight volume contraction of roughly 22 mL for this specific water-ethanol blend, your final mixed solution amount will total approximately 1,478 mL at precisely 40% ABV.

Always add your strong alcohol into the water, rather than pouring water into the high-proof spirit, to minimize unexpected exothermic reactions and splashing. Use distilled or deionized water to prevent unwanted mineral cloudiness or off-flavors in consumable beverages. Finally, always measure your liquids by weight or use accurate volumetric glassware, as temperature fluctuations can significantly alter liquid density and final ABV readings.