Why use this calculator
Whether you are making cocktails, diluting spirits for bottling, or adjusting homebrew, knowing exactly how much water to add prevents over-dilution and wasted product.
How to use it
Enter the current ABV percentage, your desired target ABV, and the volume of liquid you are starting with. The calculator shows how much water to add and the resulting final volume.
The formula
Water to add = volume * (currentABV / targetABV - 1); Proof = ABV * 2
Worked examples
Dilute 750ml of 40% ABV spirit to 20%
Add 750 ml water for 1500 ml total at 20% ABV (40 proof)
Dilute 500ml of 60% ABV to 40%
Add 250 ml water for 750 ml total at 40% ABV (80 proof)
When people use it
- Reducing cask-strength whisky to drinking strength
- Preparing cocktail bases at specific ABV levels
- Homebrew spirit dilution after distillation
- Making limoncello or infused spirits at the right strength
Tips
- Always add water to spirit, not spirit to water, for better mixing
- Use distilled or filtered water for the cleanest result
- Dilution can make some spirits cloudy temporarily, this is normal and clears with time
- US proof is simply ABV multiplied by 2
Questions people ask
- What is Pearson's Square method?
- Pearson's Square is a visual method for calculating blend ratios. For simple dilution with water (0% ABV), it simplifies to the formula: water = volume * (currentABV/targetABV - 1).
- Does temperature affect the dilution?
- Slightly. Alcohol and water contract when mixed, so the final volume may be marginally less than calculated. For home use, the difference is negligible.