Alcohol Percentage Calculator
Use these three quick tools to estimate alcohol by volume (ABV) for brewing, drink blending, and dilution.
1) Homebrew ABV (Original Gravity / Final Gravity)
Formula used: ABV = (OG - FG) × 131.25
2) Blend Two Drinks (Final ABV)
Enter any consistent volume unit (ml, oz, liters). The calculator works as long as both volumes use the same unit.
3) Dilution Calculator (Add Water)
Based on C1V1 = C2V2. Great for lowering spirit strength.
What is alcohol percentage (ABV)?
Alcohol percentage usually means ABV, or alcohol by volume. An ABV of 12% means 12% of the liquid volume is pure alcohol. ABV is the most common way to compare beer, wine, spirits, cocktails, and homemade batches.
In some regions, you may also see proof. In the U.S., proof is simply double ABV (for example, 40% ABV = 80 proof).
When to use each calculator
Homebrew ABV (OG/FG)
If you brew beer, cider, mead, or wine, your hydrometer readings are the fastest way to estimate final alcohol content. You enter:
- OG: gravity before fermentation
- FG: gravity after fermentation
The greater the drop from OG to FG, the more sugar was converted, and the higher the ABV.
Blend Two Drinks
This is useful when combining liquids with different strengths. For example, mixing spirits with beer, wine with juice, or pre-batched cocktails. The calculator returns your final ABV and total pure alcohol amount.
Dilution (Water Addition)
Need to reduce strength? This mode tells you how much water to add to reach a target ABV. It is commonly used for adjusting spirits before bottling or balancing strong infusions.
Key formulas used
- Brewing estimate: ABV = (OG − FG) × 131.25
- Blend ABV: Final ABV = (Alcohol from drink 1 + Alcohol from drink 2) ÷ Total volume
- Dilution: C1V1 = C2V2
These formulas are practical and widely used, but remember they are estimates. Lab measurements are needed for exact legal/production labeling.
Tips for better accuracy
- Use clean measurement tools and read meniscus levels carefully.
- Check hydrometer temperature corrections when brewing.
- Keep units consistent (all ml, all oz, or all liters).
- Round only at the end to avoid compounding errors.
- Record every batch so you can improve consistency over time.
Common mistakes to avoid
- Entering ABV as a decimal (0.40) instead of percent (40).
- Using different units for volume in the same calculation.
- Setting a dilution target ABV that is higher than your current ABV.
- Typing OG lower than FG in fermentation calculations.
Quick example
Suppose your beer starts at OG 1.060 and finishes at FG 1.012:
ABV = (1.060 − 1.012) × 131.25 = 6.30%
That puts it in a common range for many IPAs and stronger ales.
Final note
This alcohol percentage calculator is designed for planning and educational use. If you produce beverages commercially, always follow local regulations, approved testing methods, and labeling requirements.