ABV Calculator
Alcohol by volume (ABV) from original and final gravity, by (OG − FG) × 131.25 or an alternate formula, with attenuation and estimated calories. How it works
Use the ABV Calculator
About the ABV Calculator
An original gravity of 1.050 and a final gravity of 1.010 give 5.25% alcohol by volume by the standard homebrew formula, ABV = (OG − FG) × 131.25, with 80.0% apparent attenuation. This ABV calculator also offers an alternate formula, which gives 5.34% for the same readings.
ABV, attenuation and calories for common gravity readings
| OG to FG | Standard ABV | Alternate ABV | Apparent attenuation | Calories per 12 US fl oz |
|---|---|---|---|---|
| 1.040 to 1.010 | 3.94% | 3.95% | 75.0% | 131 |
| 1.050 to 1.010 | 5.25% | 5.34% | 80.0% | 165 |
| 1.060 to 1.012 | 6.30% | 6.51% | 80.0% | 201 |
| 1.070 to 1.015 | 7.22% | 7.59% | 78.6% | 237 |
| 1.080 to 1.016 | 8.40% | 8.96% | 80.0% | 274 |
| 1.090 to 1.018 | 9.45% | 10.25% | 80.0% | 312 |
| 1.100 to 1.020 | 10.50% | 11.58% | 80.0% | 351 |
| 1.120 to 1.025 | 12.47% | 14.24% | 79.2% | 432 |
Readings as entered, with no temperature correction. The calories are the page’s estimate from an equation found only on secondary homebrewing sources.
Methodology
Standard: ABV = (OG − FG) × 131.25. Alternate: ABV = 76.08 × (OG − FG) ÷ (1.775 − OG) × (FG ÷ 0.794). Apparent attenuation = (OG − FG) ÷ (OG − 1) × 100. ABV prints to two decimals and attenuation to one. The page accepts an OG of 1.000 to 1.180 and an FG from 0.990 up to the OG. Readings in degrees Plato convert by SG = 260.4 ÷ (260.4 − °P), so 12.4 °P is 1.050. With a sample temperature typed in, both readings are corrected by the VinoCalc fit, reading × f(sample °F) ÷ f(calibration °F), before the ABV is worked out.
Frequently asked questions
- How do you calculate ABV from gravity readings?
- Subtract the final gravity from the original gravity and multiply by 131.25. A beer that starts at 1.060 and finishes at 1.012 is (1.060 − 1.012) × 131.25 = 6.30% ABV.
- Which ABV formula should I use?
- Both are approximations. Brewer’s Friend quotes the two and says to use the standard one if you are unsure. They give nearly the same answer for ordinary beers, 3.94% and 3.95% for 1.040 to 1.010, and part ways for strong ones: 1.100 to 1.020 gives 10.50% against 11.58%.
- What is apparent attenuation?
- The share of the gravity points above 1.000 that fermentation removed: (OG − FG) ÷ (OG − 1). From 1.050 to 1.010 is 40 of 50 points, 80.0%. It is called apparent because the final reading is taken with alcohol in the beer, and alcohol is less dense than water.
- How many calories are in homebrew beer?
- For 1.050 to 1.010 the page estimates 165 calories per 12 US fl oz bottle, 154 per 330 mL bottle, 233 per 500 mL bottle and 220 per 16 US fl oz pint. A stronger beer of 1.080 to 1.016 comes to 274 per 12 oz.
- Why is my final gravity below 1.000?
- Alcohol is lighter than water (ethanol is about 0.789 g/cm³), so a cider, wine or mead that ferments almost all its sugar can read under 1.000. The FG field accepts readings down to 0.990. A cider from 1.050 to 0.998 is 6.83% ABV, and apparent attenuation shows above 100%, 104.0%, because the reading fell past the 1.000 line.
- Do I need to correct a hydrometer reading for temperature?
- Yes, when the sample is far from the temperature the hydrometer is calibrated at, usually 68 °F (20 °C) on newer ones and 59 °F (15 °C) on older ones. Type the sample temperature and the page corrects both readings with the widely used VinoCalc fit, a rule of thumb rather than a standard: 1.050 and 1.010 read at 80 °F on a 68 °F hydrometer become 1.05162 and 1.01156, 5.26% ABV instead of 5.25%. The ABV barely moves when both readings share one temperature, but each corrected gravity does.
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