Calculate how much water to add to a high-proof spirit to reach your desired alcohol concentration.
Last updated: March 2026
Example: 95 for neutral grain spirit (NYS spirit = 95% ABV)
Example: 1000 ml (1 liter). Must be positive.
Example: 40 for vodka or gin. Must be lower than initial strength.
Ignores ~0.5-3% contraction
Alcohol dilution is the process of reducing the concentration of ethanol in a spirit by adding a solvent, typically distilled or purified water. This is a standard practice in distilling, where spirits are often distilled to very high proofs (80-95% ABV) and then "cut" to bottling strength (usually 40-50% ABV).
The calculation relies on the principle of conservation of mass. Since we are only adding water, the total amount of pure alcohol remains the same, but it is spread across a larger total volume, thus lowering the percentage. Note: This is an inexpensive approximation model that ignores volume contraction (typically 0.5-3% when mixing alcohol and water).
⚠️ Approximation Model: This formula ignores volume contraction (~0.5-3%) that occurs when mixing alcohol and water. For precise distillery work, use professional hydrometers or ABV meters.
Let's dilute 1 liter of 95% spirit to 40%:
Step 1: (95 × 1000) / 40 = 2375 ml (Final Volume)
Step 2: 2375 - 1000 = 1375 ml
Final Answer: Add 1375 ml of water to the original liter.
YES. When mixing alcohol and water, molecules 'nest' together, resulting in final volume 0.5-3% LESS than expected. This calculator ignores contraction for simplicity. Professional distillers use hydrometer tables or ABV meters for precision.
Initial inputs are numeric (number type). Results display as strings (text) after formatting to 2 decimal places for readability. Internally, calculations remain numeric to prevent type errors in downstream use.
Distilled or reverse osmosis (RO) water is best. Tap water contains minerals that can cause 'floc' (cloudiness) when added to high-proof spirits. Never use chlorinated tap water.
Always add SPIRIT to WATER (never water to high-proof alcohol). This prevents exothermic reactions and temporary cloudiness. Pour the spirit slowly into the water while stirring gently.
ABV (Alcohol by Volume) is the percentage. In the US, Proof = 2 × ABV (e.g., 40% ABV = 80 Proof). In the UK/Canada, Proof uses a different scale (70 Proof UK ≈ 40% ABV).
Results are rounded to 2 decimal places for display but calculated as full-precision decimals internally. For bottles and consumer products, this ~0.01 ml error is negligible. For laboratory work, use a calibrated pipette and test with an ABV meter.
No. This calculator requires 0 < Target < Initial Strength. You cannot concentrate by diluting, and 0% or 100% are edge cases with no practical meaning.
If water needed exceeds several liters, double-check your initial volume unit. A warning appears if volume exceeds 100L. Verify you're using ml (not gallons or liters) consistently.
For rough estimates: multiply the starting ABV by the starting volume, then divide by target ABV. But always verify with the calculator—rounding errors compound quickly in spirits bottling.
This calculator ignores ~0.5-3 percent contraction for simplicity. Professional distillers use hydrometer tables or calibrated ABV meters to test actual final strength. For home use, the approximation is acceptable; for commercial bottling, use verified lab measurements.
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