ABV calculator
This ABV calculator works out the alcohol content from original and final gravity for beer, wine or mead, or for drinks you mix yourself. At 1.050 and 1.010 you get about 5.3 % ABV.
Example: What would you like to calculate: Fermentation: beer, wine, mead · Reading in: Gravity (SG, e.g. 1.050) · Original gravity (before fermentation) 1.05 · Final gravity (after fermentation) 1.01 → Alcohol content: About 5.3 % ABV. Source: Wikipedia – Alcohol by volume (ABV from specific gravity, formulas for beer and wine). Updated: .
How it is calculated
During fermentation yeast turns sugar into alcohol and carbon dioxide, and the density of the liquid falls. From the density before (original gravity) and after fermentation (final gravity) you can estimate the alcohol content.
The formulas
The simple rule of thumb is ABV = (OG − FG) × 131.25, with OG the gravity before fermentation and FG after. Hall’s formula is more accurate: ABV = 76.08 × (OG − FG) / (1.775 − OG) × (FG / 0.794). It allows for alcohol being lighter than water and differs noticeably from the simple one for strong beers and wines. The calculator converts Plato and Oechsle to gravity: Oechsle is (gravity − 1) × 1000, and Plato follows the usual approximation formula.
Mixed drinks
When mixing, what counts is the pure alcohol: amount times percentage, divided by the total amount. 40 ml of vodka at 40 % and 100 ml of juice give about 11.4 % ABV. In reality the volume shrinks slightly on mixing, so the true content is marginally higher.
- Apparent attenuation: the share of extract that was fermented, ignoring the effect of the alcohol itself.
- Hydrometers are usually calibrated for 20 °C; at other temperatures the reading is off.
- This is a helper for home brewers and not an official measurement.
Frequently asked questions
How do you calculate the ABV of homebrew beer?
Gravity before fermentation minus gravity after, times 131.25. From 1.050 and 1.010 that gives 5.25 % ABV; Hall’s more accurate formula gives about 5.3 %.
How do you convert Plato to alcohol?
Plato is first converted to gravity (12 °P is about 1.048) and then used as above. The calculator does both steps.
How do I work out the ABV of a cocktail?
Choose “Mix” and enter the amount and alcohol content of each ingredient. The sum of amount times percentage, divided by the total amount, gives the content.
Sources and legal basis
- Wikipedia – Alcohol by volume (ABV from specific gravity, formulas for beer and wine)
- Wikipedia – Stammwürze (original gravity: degrees Plato, relation to density)
- Wikipedia – Oechslegrad (Oe = (Dichte − 1) · 1000)
- Wikipedia – Ethanol (density 0.789 g/ml at 20 °C)
As of: · Editorial policy
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