ABV Dilution Calculator — Dilute Spirits to Target ABV
Calculate exactly how much water to add to dilute any spirit from a starting ABV% down to a target ABV%. Supports fluid ounces and milliliters. Essential for home distillers, craft brewers, and winemakers.
How to use it
- Select your volume unit: oz or mL.
- Enter the starting ABV percentage of your spirit.
- Enter the target ABV you want to reach.
- Enter the volume of spirit you are starting with.
- Read the amount of water to add and the final volume.
ABV vs. Proof
ABV (Alcohol By Volume) is the percentage of alcohol in a liquid. Proof is ABV × 2 in the US system. This calculator uses ABV directly — if you know the proof, divide by 2 to get ABV.
Volume Contraction When Diluting Spirits
When you mix alcohol and water, the total volume is slightly less than the sum of the two volumes due to molecular interactions. For home use, this difference is negligible. For TTB compliance, use official gauging tables.
The formula
Frequently asked questions
How do I dilute 95% alcohol to 40% ABV?
Water = Volume × (95/40 − 1) = Volume × 1.375. For 1 liter of 95% alcohol, add 1.375 liters of water to get 2.375 liters at 40% ABV.
What ABV is 80 proof?
80 proof = 40% ABV. In the US, proof is always exactly twice the ABV percentage.
Can I use tap water for dilution?
Distilled or filtered water is recommended for spirits to avoid introducing chlorine or mineral flavors.
What is the minimum bottling ABV for bourbon?
US law requires bourbon to be bottled at no less than 40% ABV (80 proof).