ABV Calculator
Enter your original gravity (OG) and final gravity (FG) to estimate alcohol by volume for beer, mead, wine and cider. Updates instantly as you type.
Gravity unit
Formula
Estimated ABV
5.25%
Suggested formula for this gravity drop: Standard.
How it works
Original gravity (OG) is the density of your must, wort or juice before fermentation starts; final gravity (FG) is the density after fermentation finishes. Yeast converts sugar into alcohol and CO₂, which lowers the gravity: the bigger the drop, the higher the alcohol.
This calculator supports four formulas: the widely used standard formula, a wine-tuned formula, a high-gravity formula for large gravity drops, and the HMRC estimate used for UK duty calculations.
ABV formulas explained
The calculator picks one of these automatically based on your gravity drop, but you can switch formulas at any time.
Standard
ABV = (OG − FG) × 131.25
The most widely used formula and the default for most beer and low-to-moderate gravity fermentations, up to roughly a 45-point gravity drop. Example: OG 1.050 and FG 1.010 gives (1.050 − 1.010) × 131.25 ≈ 5.25% ABV.
Wine
ABV = (OG − FG) × 136
Same shape as the standard formula but tuned for wine and mead, which typically ferment drier and at higher gravity. Suggested for gravity drops between roughly 46 and 70 points.
High-gravity (alternate)
ABV = (76.08 × (OG − FG) / (1.775 − OG)) × (FG / 0.794)
A non-linear formula that stays accurate for large gravity drops, above roughly 70 points, for strong meads or barleywines, where the standard formula tends to underestimate.
HMRC estimate
points = (OG − FG) × 1000, ABV = points × 0.125–0.135
The UK tax-authority method, used mainly for duty calculations rather than everyday tracking. The factor steps up with the size of the drop: 0.125 up to 35 points, 0.13 up to 45 points, and 0.135 above that.
Quick reference: OG → FG → ABV%
Common OG/FG combinations using the standard formula. Enter your own readings above for an exact result, or switch formulas for high-gravity meads and wines.
| OG \ FG | 1.000 | 1.005 | 1.010 | 1.015 | 1.020 |
|---|---|---|---|---|---|
| 1.040 | 5.25% | 4.59% | 3.94% | 3.28% | 2.63% |
| 1.050 | 6.56% | 5.91% | 5.25% | 4.59% | 3.94% |
| 1.060 | 7.88% | 7.22% | 6.56% | 5.91% | 5.25% |
| 1.070 | 9.19% | 8.53% | 7.88% | 7.22% | 6.56% |
| 1.080 | 10.50% | 9.84% | 9.19% | 8.53% | 7.88% |
| 1.090 | 11.81% | 11.16% | 10.50% | 9.84% | 9.19% |
| 1.100 | 13.13% | 12.47% | 11.81% | 11.16% | 10.50% |
Frequently asked questions
How do I calculate ABV from OG and FG?
The standard formula is (OG − FG) × 131.25. For example, an original gravity of 1.050 and a final gravity of 1.010 gives (1.050 − 1.010) × 131.25 ≈ 5.25% ABV. This calculator does the math for you and also offers wine, high-gravity and HMRC estimate formulas.
Which ABV formula should I use?
This calculator offers four formulas (standard, wine, high-gravity and HMRC estimate) and suggests one automatically based on your gravity drop, which you can always override. See the formula breakdown above for the exact math and when each one applies.
Why is my ABV different from another calculator?
Small differences between calculators are normal: different formulas trade off accuracy differently as the gravity drop gets larger. At low-to-moderate gravity drops the formulas mostly agree; at high gravity (strong meads, big wines) the standard formula tends to underestimate ABV, which is why a high-gravity or wine formula is usually more accurate there.
Is this ABV calculation exact?
It is a close estimate, not a lab measurement. Accuracy depends on how precisely you read your hydrometer or refractometer and on correcting for temperature. For most home fermentation tracking it is more than accurate enough.
Related tools
Track the whole batch, not just the math
Fermolog logs your gravity readings, ABV, notes and photos automatically as you go. Download the free app to keep every batch in one place.