# How ABV dilution works
Dilution reduces the alcohol concentration by adding water while keeping the amount of pure alcohol approximately constant. This ABV dilution calculator turns a starting strength and volume into a practical water addition and a theoretical final volume. It works locally in the browser with no uploaded batch data.| Value | Formula | Meaning |
|---|---|---|
| Pure alcohol | starting volume x starting ABV | Alcohol carried into the blend |
| Final volume | pure alcohol / target ABV | Theoretical total after dilution |
| Water to add | final volume - starting volume | The planning amount of water |
# ABV and proof conversion
Alcohol by volume expresses pure alcohol as a percentage of the liquid volume. US proof is twice the ABV, which makes 40 percent ABV equal to 80 proof. Use the visible strength switch when a bottle label uses proof, but remember that proof systems can differ by country and historical convention. 80 proof 40 percent ABV
1:1 Water ratio in the default scenario
100% local No batch data uploaded
# Why the result is an estimate
The arithmetic preserves the pure alcohol volume, but real mixtures are not perfectly additive. Alcohol and water contract as they combine, and temperature changes density and measured volume. For repeatable production, add water gradually, allow the blend to reach the intended temperature, and verify strength with equipment suited to the liquid.Blend gradually and verify
Use clean, measured water and a container large enough for the theoretical final volume. The calculator does not know your temperature, sugar, flavourings, or local measurement rules, so treat its water amount as a starting plan rather than a certificate of final ABV.# A repeatable dilution workflow
- Record the labelled starting ABV and the actual batch volume.
- Choose a target strength that is lower than the starting strength.
- Calculate pure alcohol, theoretical final volume, and water to add.
- Add most of the water, mix, then add the remainder in small measured steps.
- Verify the finished blend after it reaches the measurement temperature.
Arithmetic is not a production approval
This page does not validate ingredients, sanitation, labelling, tax, licensing, or legal sale. Never use a calculator result as a reason to skip the rules and checks that apply to your beverage or location.