What does this tool do?
The alcohol in a drink is the starting volume multiplied by its strength. Adding a non-alcoholic liquid keeps the alcohol constant and raises the total volume, which lowers the strength. This calculator finds the water needed for a target ABV.
The Formula
C1 × V1 = C2 × V2, so water to add = V1 × (C1 ÷ C2 − 1)Frequently Asked Questions
Can I use this for beer or wine?
Yes, for a rough estimate. Beer and wine already contain water and alcohol, so treat the labelled ABV as the starting strength and add a non-alcoholic mixer such as soda or juice.
Why is the final volume slightly different in practice?
Water and ethanol molecules pack together more tightly than the ideal model assumes, and the mixture warms or cools slightly. The difference is small for normal serving volumes.