Alcohol Dilution Calculator 2026
Calculate exactly how much water to add to reach your target ABV, or find the new ABV after adding a mixer. Includes volume contraction correction for precise home distilling and bartending.
Dilution Settings
Enter your initial spirit details and choose what to calculate
The total volume of your starting spirit
Alcohol By Volume of your starting spirit (e.g., 95% for neutral spirit, 40% for vodka)
The ABV you want to achieve by adding water
Dilution Results
Water needed, final volume, and new ABV
Enter your initial spirit details and click Calculate Dilution to see how much water to add or your new ABV.
Common Dilutions at a Glance
How much water to add to 1 Litre of high-proof spirit to reach common drinking strengths. Values assume ideal mixing without volume contraction.
| Initial ABV | Target ABV | Water to Add (per 1L) | Typical Use |
|---|---|---|---|
| 95% | 40% | 1,375 ml | Standard vodka / whisky bottling |
| 95% | 45% | 1,111 ml | Navy strength gin (approx) |
| 75% | 40% | 875 ml | Diluting high-wines |
| 60% | 40% | 500 ml | Cask strength whisky dilution |
| 50% | 40% | 250 ml | Minor ABV adjustment |
| 95% | 20% | 3,750 ml | Liqueur base preparation |
| 40% | 15% | 1,667 ml | Low-ABV spritz base |
Alcohol Dilution FAQ
Everything you need to understand alcohol dilution, from the basic formula to real-world distilling phenomena like volume contraction.
Alcohol dilution is calculated using the formula Vwater = Vinitial × (ABVinitial – ABVtarget) / ABVtarget. This determines the exact volume of water (or 0% ABV mixer) needed to reduce your spirit to the desired strength.
Volume contraction occurs when mixing ethanol and water. The molecules form hydrogen bonds and pack more tightly together, resulting in a total volume that is 2-4% less than the sum of the two separate volumes. Our calculator includes an optional correction for this phenomenon to give you the most accurate final ABV.
In the US, Proof is simply double the ABV (e.g., 40% ABV = 80 Proof). In the UK, the historical proof system multiplied ABV by 1.75 (e.g., 40% ABV = 70° Proof). You can enable proof display in our calculator’s advanced options.
This calculator is optimized for diluting a single spirit with water (0% ABV). To mix two spirits of different strengths, use the general mixing formula: ABVfinal = (V1 × ABV1 + V2 × ABV2) / (V1 + V2).
Yes. Alcohol expands more than water when heated. Standard ABV is measured at 20°C (68°F). If your spirit is warmer than 20°C, a hydrometer will read a lower ABV than the true content. For precise distilling, always temperature-correct your hydrometer readings.