ABV Dilution Calculator
Use this ABV dilution calculator to lower alcohol by volume with water. Enter the current ABV, your volume, and the ABV you want — it returns the exact water to add and the final volume.
Enter the current ABV, your volume, and the ABV you want to get the water to add.
How to lower ABV with water
Adding water does not change the amount of pure alcohol, only the total volume, so the dilution equation holds with ABV as the concentration:
C₁ is the current ABV, V₁ is your volume, and C₂ is the target ABV. The final volume is V₂ = C₁ × V₁ ÷ C₂, so the water to add is:
Worked example
You have 500 mL at 50% ABV and want 40%: water = 500 × (50 ÷ 40 − 1) = 125 mL, giving 625 mL at 40% ABV. Add water gradually and confirm with a hydrometer, since temperature affects the reading.
Quick ABV multiplier chart
For common before/after ABV pairs, the water multiplier is fixed — no need to run the calculator for these:
| ABV change | Water to add |
|---|---|
| 60% → 40% | 0.50× your volume in water |
| 50% → 40% | 0.25× your volume in water |
| 40% → 20% | 1.00× your volume in water |
| 96% → 40% | 1.40× your volume in water |
| 12% → 5% (wine spritzer) | 1.40× your volume in water |
Related tools
This is the ABV-focused version of the alcohol dilution calculator. For any solution rather than spirits, use the home dilution calculator.
Frequently asked questions
›How do I lower ABV by adding water?
Water to add = V₁ × (C₁ ÷ C₂ − 1), where C₁ is the current ABV, C₂ is the ABV you want, and V₁ is your current volume. Adding water raises the total volume while the pure alcohol stays constant, so the ABV falls.
›What is the ABV dilution formula?
Alcohol is conserved on dilution, so C₁V₁ = C₂V₂. The final volume is V₂ = C₁ × V₁ ÷ C₂, and the water to add is V₂ − V₁. For example, 500 mL at 50% ABV down to 40%: water = 500 × (50 ÷ 40 − 1) = 125 mL.
›Is there a simple ABV dilution chart?
The multiplier is C₁ ÷ C₂ − 1 times your volume. From 60% to 40% you add 0.5× the volume of water; from 50% to 40% you add 0.25×; from 40% to 20% you add 1.0× (an equal volume of water). The calculator gives the exact figure for any pair.
›Is this ABV dilution calculator free?
Yes. It runs entirely in your browser, needs no sign-up, and never sends your numbers to a server.
›How is this different from the alcohol dilution calculator?
Same maths (C₁V₁ = C₂V₂ with ABV as the concentration) — this page is built around quick before/after ABV pairs rather than a single spirit-proofing workflow. Use whichever framing matches how you think about the problem.
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