Wine & Mead Gravity to ABV Calculator
Enter your starting and finishing gravity readings to find out how strong your wine or mead is. Compare three calculation methods, check fermentation progress, and log batches - all in your browser. Nothing uploaded.
ABV Results
Learn more: gravity, fermentation, and alcohol by volume
Original gravity vs final gravity and what yeast does
Original gravity (OG) is the density of your juice before fermentation - measured in specific gravity (1.050 means 1050 points above water). Yeast eats the sugars and produces alcohol and carbon dioxide. Final gravity (FG) is the density after fermentation is complete. The difference between OG and FG tells you how much sugar was consumed. Higher OG juice produces more alcohol - wine yeast can typically survive up to 14-18 percent ABV depending on the strain.
How ABV is calculated and why the formula matters
Alcohol by volume (ABV) is calculated as approximately 0.1808 times (OG minus FG). This formula assumes standard yeast efficiency and fermentation conditions. A wine starting at OG 1.100 and finishing at 1.010 produces roughly 14.4 percent ABV. Different yeast strains, temperatures, and nutrients affect how much sugar is actually fermented, so real-world ABV can vary slightly from calculated.
Using gravity measurements to predict fermentation completion
Hydrometers and refractometers measure gravity. Fermentation is complete when gravity stops dropping for 3-5 days. Most home winemakers target residual gravity between 0.990-1.005 for dry wine, or higher (1.010-1.030) for sweet wine. Bottling too early (incomplete fermentation) can cause bottle bombs if yeast restarts. Bottling too late (over-fermented) can produce off-flavors.
FAQ
What is specific gravity and how do I measure it?
Specific gravity is the ratio of liquid density compared to water (which is 1.000). Juice with 50 grams of dissolved sugar per litre is about 1.050 SG. Use a hydrometer (floats in liquid and reads directly) or refractometer (small prism instrument) to measure. Always take readings at the same temperature for accuracy.
How much alcohol will my fermentation produce?
Multiply (OG minus FG) by approximately 1000 to get the alcohol-equivalent points, then divide by 12.7 to get percent ABV. For example: OG 1.100, FG 1.010 gives (0.100 * 1000) divided by 12.7, roughly 7.9 percent ABV per 100 points, or about 14.4 percent total.
When is fermentation complete?
Fermentation is complete when gravity readings are stable (no change over 3-5 days) and typically reaches 0.990-1.005 SG for dry wine. Some residual sugar may remain if yeast stress or high alcohol kills the yeast early. Bottling too early risks bottle bombs; too late risks oxidation or off-flavors.