ABV Calculator: Alcohol by Volume From OG and FG
Enter your original and final gravity for ABV, alcohol by weight, attenuation and calories. Took the reading warm? It corrects for temperature too.
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How to use it
- ABV from OG and FG: enter the gravity before you pitched the yeast (OG) and the gravity once fermentation finished (FG), in specific gravity or degrees Plato. A beer that goes from 1.050 to 1.010 is 5.3% ABV.
- Readings taken warm or cold? Tick the temperature box and enter the sample temperature for each reading. Hydrometers read true only at the temperature they were calibrated for, usually 60°F or 68°F.
- Just correcting one reading: switch to “Correct a hydrometer reading”, for example a wort sample pulled hot on brew day.
The ABV formula
The quick formula most brewers know is ABV = (OG − FG) × 131.25. For 1.050 to 1.010 that is 5.25%.
It reads low for strong beers, so this calculator uses the more accurate version:
ABV = 76.08 × (OG − FG) ÷ (1.775 − OG) × (FG ÷ 0.794)
For a normal-strength beer the two agree within about 0.1%. For a double IPA that goes from 1.090 to 1.018, the quick formula gives 9.5% and the accurate one 10.3%. The calculator shows both.
ABV chart
Find your original gravity on the left and your final gravity across the top.
| OG \ FG | 1.000 | 1.004 | 1.008 | 1.012 | 1.016 | 1.020 | 1.024 |
|---|---|---|---|---|---|---|---|
| 1.030 | 3.9% | 3.4% | 2.9% | 2.3% | 1.8% | – | – |
| 1.040 | 5.2% | 4.7% | 4.2% | 3.7% | 3.2% | 2.7% | – |
| 1.050 | 6.6% | 6.1% | 5.6% | 5.1% | 4.6% | 4.0% | 3.5% |
| 1.060 | 8.0% | 7.5% | 7.0% | 6.5% | 6.0% | 5.5% | 4.9% |
| 1.070 | 9.5% | 9.0% | 8.5% | 8.0% | 7.5% | 6.9% | 6.4% |
| 1.080 | 11.0% | 10.5% | 10.0% | 9.5% | 9.0% | 8.4% | 7.9% |
| 1.090 | 12.6% | 12.1% | 11.6% | 11.0% | 10.5% | 10.0% | 9.5% |
| 1.100 | 14.2% | 13.7% | 13.2% | 12.6% | 12.1% | 11.6% | 11.0% |
| 1.110 | 15.8% | 15.3% | 14.8% | 14.3% | 13.8% | 13.2% | 12.7% |
ABV by original gravity (left) and final gravity (top). Blank cells would be a badly stuck fermentation.
Hydrometer temperature correction chart
Warm liquid is less dense, so a hydrometer sinks deeper and reads low. Add these points to what you read. For a reading at the calibration temperature, add nothing.
| Sample temperature | Hydrometer calibrated at 60°F (15.6°C) | Hydrometer calibrated at 68°F (20°C) |
|---|---|---|
| 50°F (10°C) | −0.7 | −1.5 |
| 60°F (16°C) | 0 | −0.8 |
| 68°F (20°C) | +0.8 | 0 |
| 70°F (21°C) | +1.1 | +0.2 |
| 75°F (24°C) | +1.7 | +0.9 |
| 80°F (27°C) | +2.4 | +1.6 |
| 85°F (29°C) | +3.3 | +2.4 |
| 90°F (32°C) | +4.1 | +3.3 |
| 100°F (38°C) | +6.1 | +5.3 |
| 110°F (43°C) | +8.4 | +7.6 |
| 120°F (49°C) | +11.0 | +10.1 |
| 130°F (54°C) | +13.8 | +12.9 |
| 140°F (60°C) | +16.8 | +15.9 |
| 150°F (66°C) | +20.0 | +19.2 |
| 160°F (71°C) | +23.5 | +22.7 |
Gravity points to add (0.001 each) to a reading of about 1.050. Example: 1.046 read at 90°F on a 60°F hydrometer is really 1.050.
Questions
How do you calculate ABV from OG and FG?
Subtract the final gravity from the original gravity and multiply by 131.25. A beer from 1.050 to 1.010 is (1.050 − 1.010) × 131.25 = 5.25% ABV. For beers above about 7%, the formula 76.08 × (OG − FG) ÷ (1.775 − OG) × (FG ÷ 0.794) is more accurate; this calculator uses it.
How do I know fermentation is finished?
Take a gravity reading three days in a row. If it doesn’t change, fermentation is done and that is your final gravity. Bubbles in the airlock aren’t a reliable sign either way.
Does temperature affect hydrometer readings?
Yes. A hydrometer reads true only at its calibration temperature, usually 60°F (15.6°C) or 68°F (20°C). Warmer samples read low: 1.046 read at 90°F on a 60°F hydrometer is really about 1.050. Cool hot samples to under 100°F (38°C) before reading, then correct with the chart or calculator.
Can I use a refractometer to measure ABV?
For the original gravity, yes. Once fermentation starts, alcohol bends light differently from sugar, so a raw refractometer reading of the finished beer is wrong. The refractometer calculator corrects for that.
What is the difference between ABV and ABW?
ABV is the share of the beer’s volume that is alcohol; ABW is the share of its weight. Alcohol is lighter than water, so ABW is always the smaller number: about 0.8 × ABV for beer. The calculator shows both.
What do apparent and real attenuation mean?
Apparent attenuation is how much of the gravity the yeast removed, as your hydrometer sees it. Most beers land at 70–80%. Real attenuation is lower, because the alcohol in finished beer makes the hydrometer read lower than the sugar left alone would.
How many calories are in my homebrew?
Mostly from the alcohol and the leftover sugars. A 5.3% beer from 1.050 to 1.010 has about 164 calories per 12 oz. The calculator works it out from your readings, with carbohydrates.