Alcohol by Volume (ABV) Calculator

ABV Formula (Standard):

ABV = (OG - FG) × 131.25

ABV Formula (More Accurate):

ABV = (76.08 × (OG - FG) / (1.775 - OG)) × (FG / 0.794)

Where:

• OG = Original Gravity — the density of your wort or must before fermentation begins. You measure this with a hydrometer or refractometer on brew day.
• FG = Final Gravity — the density after fermentation is complete. When the reading stays the same for 2-3 days in a row, fermentation has finished.

The standard formula is a quick estimate that works well for most homebrews. The advanced formula accounts for the changing density of alcohol in the solution and gives more accurate results, especially for high-gravity brews above 8% ABV.

Gravity Reference:

• Water = 1.000
• Typical beer OG: 1.035 - 1.090
• Typical wine OG: 1.070 - 1.120
• Typical mead OG: 1.080 - 1.130

Practical Example: If you brew a beer with OG = 1.055 and FG = 1.012: Standard: (1.055 - 1.012) x 131.25 = 5.64% ABV The advanced formula gives approximately 5.67% ABV for the same readings.

Common ABV Ranges:

Apparent Attenuation: This tells you what percentage of sugars the yeast consumed. Attenuation = (OG - FG) / (OG - 1.000) × 100% Most healthy fermentations achieve 70-80% apparent attenuation.

Common Mistakes:

• Forgetting to temperature-correct your hydrometer reading (most are calibrated to 60F / 15.6C)
• Taking the FG reading before fermentation is truly complete
• Confusing Brix/Plato readings with specific gravity — they are different scales