Whiskey Proofing Calculator — How Much Water to Add
Calculate exactly how much water to add to your whiskey or spirit to reach a desired proof. Works in fluid ounces or milliliters. Used by home distillers, whiskey enthusiasts, and craft distilleries.
How to use it
- Select your preferred volume unit: oz or mL.
- Enter the current proof of your whiskey (e.g., 100 proof = 50% ABV).
- Enter your desired target proof (e.g., 80 proof = 40% ABV).
- Enter the volume of whiskey you are starting with.
- Read the exact amount of water to add and the final volume.
What Is Proof?
In the United States, proof is exactly twice the ABV percentage. 100-proof whiskey is 50% alcohol by volume. 80-proof (the standard for most commercial whiskeys) is 40% ABV.
Why Add Water to Whiskey?
Adding a few drops of water to cask-strength whiskey (typically 120–140 proof) can open up the flavor by breaking apart fatty acid chains that trap aromatic compounds.
Tips for Proofing Whiskey at Home
Use filtered or distilled water — tap water chlorine can affect flavor. Add water gradually and taste as you go. For precise commercial proofing, use a calibrated hydrometer and TTB-approved gauging tables.
The formula
Frequently asked questions
How much water do I add to 100-proof whiskey to make it 80 proof?
For every 8 oz of 100-proof whiskey, add 2 oz of water: 8 × (100/80 − 1) = 2 oz. This gives you 10 oz of 80-proof whiskey.
What proof is most whiskey sold at?
Most commercial whiskeys are bottled at 80 proof (40% ABV). Bourbon must be bottled at no less than 80 proof by US law. Cask-strength releases range from 110–140+ proof.
Does adding water change the flavor of whiskey?
Yes — a small amount of water can open up aromas and soften the burn of high-proof whiskeys. Too much water can dilute the flavor.
What is the difference between proof and ABV?
In the US, Proof = ABV × 2. So 80 proof = 40% ABV. The proof system originated from a historical gunpowder test used to verify alcohol content.
Can I use this calculator for bourbon, scotch, or moonshine?
Yes — the proofing formula works for any spirit: bourbon, scotch, rum, vodka, or moonshine.