Alcohol Dilution Calculator

Cutting a spirit down to a target strength is a precise operation, and this tool tells distillers, homebrewers, and cocktail makers exactly how much water it takes to reach a chosen alcohol by volume (ABV) or proof. Hitting the number matters for batch-to-batch consistency, for label compliance, and for what lands in the glass. Overshoot and you've watered down the character; undershoot and you've missed spec.

Under the hood it's a balance of pure alcohol: (Volume of Spirit * Initial ABV) = (Total Volume * Target ABV). Rearrange that to solve for total volume, subtract the spirit you started with, and what's left is the water to add. Alcohol and water don't combine in a perfectly additive way: the mixture contracts slightly, so the finished volume is a little less than spirit plus water. The calculator treats the volumes as additive and doesn't correct for that shrinkage, which means the result can come out slightly stronger than the target, so check it with a hydrometer before bottling.

Reach for distilled or demineralized water every time, since minerals in tap water can throw a haze or off-flavors into the finished spirit. Diluting also softens flavor intensity a touch, so on small batches it pays to taste as you go rather than trust the number blind. One thing the calculation sets aside is temperature: alcohol volume shifts as it warms or cools, and US regulations define proof at 60°F (27 CFR 30.11), so take hydrometer readings at that temperature or correct them for it.