Add this much water
—
Final volume: — · Final ABV: —%
| Use case | Typical from | Typical target |
|---|---|---|
| Cask-strength whisky → drinking strength | 55–65% | 40–46% |
| Cask-strength bourbon → highball | 60% | 30–35% |
| Overproof rum → tiki cocktail base | 63% | 40% |
| Homebrew spirit (heads/tails) → bottling | 70–90% | 40% |
| Wine cooler from wine | 13% | 5–7% |
| Punch from spirit base | 40% | 8–12% |
How the math works
Alcohol mass stays constant when you dilute: V₁ × ABV₁ = V₂ × ABV₂. So target volume V₂ = V₁ × ABV₁ ÷ ABV₂, and water to add = V₂ − V₁.
This approximation ignores contraction — alcohol and water mix to slightly less than the sum of volumes (about 2–4% at high ABVs). For drinking spirits this matters by 0.2–0.5% ABV; use a hydrometer for exact bottling strength.