How It Works
This calculator works in 4 steps.
Enter the starting ABV
Type the ABV of the original beer or cider.
Enter the starting volume
Type the volume in mL, US fl oz, liters, or gallons.
Enter the added liquid
Type the volume and ABV of the water or drink added (0% for water).
Read the new ABV
The calculator returns the estimated ABV and the final volume.
The Formula
The formula divides the total alcohol volume by the total liquid volume.
ABV₂ = ABV₁ × V₁ / V₂ABV_mix = (ABV₁V₁ + ABV_aVa) / (V₁ + V_a)V_water = V₁ × (ABV₁ / ABV₂ − 1)- ABV₁ / ABV₂:
- Starting and final ABV
- V₁ / V₂:
- Starting and final volume
- ABV_a / V_a:
- ABV and volume of the added liquid
A 12 oz (355 mL) serving at 8% ABV topped up to 16 oz (473 mL) with water gives about 8 × 355 / 473 = 6.0% ABV.
Conversion Table
The conversion table estimates the new ABV for 6 starting strengths and volume changes (volumes in any shared unit).
| Starting ABV | Starting volume | Final volume | Estimated ABV |
|---|---|---|---|
| 10% | 1 | 2 | 5% |
| 8% | 355 | 473 | 6.004% |
| 12% | 5 | 6 | 10% |
| 6% | 500 | 550 | 5.455% |
| 9.5% | 20 | 25 | 7.6% |
| 14% | 1 | 1.4 | 10% |
What Is the Beer Alcohol Dilution Calculator?
The Beer Alcohol Dilution Calculator is a tool that estimates the alcohol by volume (ABV) of beer, cider, or another fermented drink after water or a non-alcoholic liquid is added. The new ABV equals the starting ABV times the starting volume, divided by the final volume.
The result is an estimate. Small volume changes on mixing alcohol and water, and the alcohol content of the added liquid, shift the real value. The calculator accepts the ABV of the added liquid, so mixing a 9% beer with a 4% beer is handled as a blend. Labeled ABV for commercial products comes from measurement, not calculation.
Common Uses
There are 5 main uses of this calculator.
High-gravity dilution
Brewers estimate ABV after diluting high-gravity beer.
Blending
Brewers estimate ABV when blending 2 beers.
Recipe testing
Homebrewers test dilution levels on small samples.
Event serving plans
Organizers estimate strength of diluted punches.
Teaching
Instructors show volume-weighted averaging.