Enter your initial alcohol volume, initial concentration, and desired concentration to find out exactly how much water to add for dilution. The Alcohol Dilution Calculator gives you the required water volume and final mixture volume — whether you're diluting spirits, isopropyl alcohol, or homemade liquor.
Water to Add
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Final Mixture Volume
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Pure Alcohol in Mixture
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Dilution Ratio (Alcohol : Water)
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To dilute alcohol, use the formula: Water to Add = Initial Volume × (Initial Concentration − Desired Concentration) / Desired Concentration. Simply measure your starting alcohol volume and concentration, decide on your target strength, and add the calculated amount of water. Mix thoroughly after adding water.
The alcohol dilution formula is based on preserving the total amount of pure alcohol. If you have a volume V₁ at concentration C₁ and want concentration C₂, the water to add is: V_water = V₁ × (C₁ − C₂) / C₂. The final volume becomes V₁ × C₁ / C₂.
Yes, you can. For every 100 mL of 91% isopropanol, add approximately 30 mL of distilled water to get close to a 70% solution. Use this calculator to get the exact amount for your specific volume. A 70% isopropyl solution is actually more effective as a disinfectant than 91% because the water helps it penetrate cell walls.
Enter 80 as your initial concentration and your target percentage (e.g. 40%) into the calculator. For example, to dilute 1000 mL of 80% alcohol to 40%, you would add 1000 mL of water, resulting in 2000 mL of 40% alcohol. The calculator handles any starting and target concentrations automatically.
Yes, water is the standard and safest way to dilute ethyl alcohol (ethanol) or isopropyl alcohol. Distilled or purified water is preferred, especially for consumable spirits, to avoid introducing minerals or contaminants that could affect flavor or purity.
Alcohol contraction is the slight reduction in total volume that occurs when alcohol and water are mixed, due to intermolecular interactions. For example, mixing 500 mL of alcohol and 500 mL of water yields slightly less than 1000 mL. For most practical purposes this is a small effect, but it can be important in precision distilling.
Yes, dissolving sugar in an alcohol-water mixture increases the total volume slightly. This means that if you're adding a sugar syrup (e.g. to make a liqueur), the actual alcohol concentration will be slightly lower than a simple dilution calculation suggests. For precise results, account for the volume contribution of the sugar syrup.
Rectified spirit (neutral grain spirit) can reach up to 96% ABV, which is essentially the azeotropic maximum for ethanol-water mixtures at atmospheric pressure. It cannot be distilled higher without special techniques. Most commercial spirits are diluted to 40–60% ABV before bottling.