An alcohol dilution calculator tells you exactly how much water to add to reduce a spirit from its current ABV to any target percentage. Used by distillers, bartenders, and spirit enthusiasts for precise proof adjustment.
Spirit Parameters
Dilution Results
Enter parameters and click Calculate
How to Use the Alcohol Dilution to Target ABV Calculator
This alcohol dilution calculator uses a simple formula: the amount of pure alcohol stays constant before and after dilution, so you can calculate exactly how much water is needed to achieve any target strength.
Step 1: Enter current volume and ABV
Enter the current volume of your spirit and its ABV percentage. ABV (alcohol by volume) is typically printed on the bottle label. Cask-strength whiskies run 55-65% ABV; standard bottlings are 40-46% ABV.
Step 2: Set your target ABV
Common target strengths: 40% (80 proof, standard US bottling), 43% (86 proof, common for Scotch), 46% (92 proof, common for quality single malts), 50% (100 proof). You cannot increase ABV by adding water — target must be lower than starting ABV.
Step 3: Add water gradually
Add water in small increments, mixing thoroughly and tasting after each addition. The formula gives you the final amount to reach exact target ABV, but add slowly and evaluate flavor at each step — you may prefer a slightly higher ABV than target.
FAQ
How do I dilute whiskey to a target ABV?
Divide the starting alcohol volume by the target ABV, then subtract the starting volume. That gives you the water to add. Example: 750ml at 60% ABV → target 40% ABV. Water to add = (750 × 0.60 / 0.40) − 750 = 1125 − 750 = 375ml.
Is this dilution calculator free?
Yes, completely free with no signup required.
Does diluting alcohol affect flavor?
Yes. Water opens up aromatic compounds by disrupting ethanol-aroma molecule clusters. Professional distillers dilute spirits to bottling proof precisely because dilution affects flavor expression. Some whisky enthusiasts add a few drops of water to release specific aromas. Too much water makes the spirit watery and flat.
What is the pearl test for whiskey dilution?
The pearl (or bead) test uses the visual pattern of bubbles that appear when you shake a spirit. High-proof spirits (above 57% ABV) form larger, longer-lasting beads. At proof (50% ABV), beads are medium. Below proof, beads are small and disappear quickly. It is an older field method but not precise enough for serious dilution work.
Can I dilute any spirit with regular tap water?
Distilled or filtered water is preferred for precision dilution because tap water minerals can interact with spirit flavor compounds. For casual use, filtered tap water is fine. Professional distillers use deionized water for consistency.