What is a mizuwari dilution calculator?
"Mizuwari" is the Japanese practice of cutting a strong spirit with water to a smooth, drinkable strength. This calculator tells you exactly how many milliliters of liquor and how many of water to combine so the finished drink reaches the alcohol strength (ABV) you want. The math is pure volume-fraction mixing, so it works for whisky, shochu, vodka or any spirit anywhere in the world.
How to use it
Enter three numbers: the desired finished strength (a tasty water-cut is typically 10-15% ABV), the total volume of the drink you want to pour (in ml), and the strength of the bottle you are pouring from. The tool returns the amount of spirit and the amount of water. The target strength must not exceed the liquor strength - you cannot make a drink stronger than its source by adding water.
The formula explained
Alcohol is conserved during mixing. The finished drink of volume \(Q\) must contain \(Q \times \text{targetAbv}\) of pure alcohol. Since the liquor supplies all of it at fraction \(\text{liquorAbv}\), the liquor needed is \(Q \times (\text{targetAbv} / \text{liquorAbv})\). The rest is water: \(Q\) minus the liquor volume. This assumes ideal additive volumes (a small real-world contraction when alcohol and water mix is ignored).
$$\begin{gathered} \text{Liquor} = \text{Total Volume} \times \frac{\text{Target ABV}}{\text{Liquor ABV}} \\[1.5em] \text{Water} = \text{Total Volume} - \text{Liquor} \end{gathered}$$
Worked example
For a 200 ml drink at 10% ABV made from a 30% spirit:
$$\text{liquor} = 200 \times \frac{10}{30} = 66.7 \text{ ml}$$$$\text{water} = 200 - 66.7 = 133.3 \text{ ml}$$Check: 66.7 ml of 30% spirit holds 20 ml pure alcohol, and \(20/200 = 10\%\). Correct.
FAQ
What is a good target strength? Most people find a mizuwari pleasant around 10-15% ABV, lighter than the original spirit.
Why is my result invalid? The target ABV is higher than the liquor ABV (impossible by dilution), or a volume/strength value is zero or negative.
Does it account for ice melt? No. If you add ice, the melting ice contributes extra water and lowers the strength further; pour slightly stronger to compensate.
