How to Calculate ABV from Gravity: Formula, Hydrometer Readings and Chart
Published November 3, 2026 · By Ahmad Parvez
Alcohol by volume is not measured directly by home equipment — it is calculated from how much the liquid's density changed while yeast turned sugar into alcohol. That density is called specific gravity: pure water is 1.000, and sugary wort, must or mash reads higher. Two readings — one before fermentation, one after — are all you need.
The ABV formula
ABV = (OG − FG) × 131.25, where OG is the original gravity (before pitching yeast) and FG is the final gravity (after fermentation finishes). The 131.25 factor converts the gravity drop into alcohol percentage and is accurate for most beers and wines up to about 10%.
For high-gravity brews (big beers, meads and wines above ~10%), the standard formula under-reads slightly. Use the alternate formula instead:
ABV = (76.08 × (OG − FG) ÷ (1.775 − OG)) × (FG ÷ 0.794)
The abv calculator runs both and shows you each result, so you can see how much the correction matters for your batch.
Worked examples
| Drink | OG | FG | Calculation | ABV |
|---|---|---|---|---|
| Pale ale | 1.050 | 1.010 | 0.040 × 131.25 | 5.25% |
| IPA | 1.064 | 1.012 | 0.052 × 131.25 | 6.83% |
| Dry wine | 1.090 | 0.995 | 0.095 × 131.25 | 12.47% |
| Mead | 1.120 | 1.020 | 0.100 × 131.25 | 13.13% |
| Session beer | 1.038 | 1.008 | 0.030 × 131.25 | 3.94% |
How to take a hydrometer reading
- Sanitise the hydrometer and test jar — a reading is not worth an infected batch.
- Fill the jar about three-quarters full and lower the hydrometer in gently; give it a spin to knock off bubbles clinging to the float.
- Read at eye level, at the bottom of the meniscus (where the liquid surface actually meets the scale), once the float settles and is not touching the sides.
- Mind the temperature. Most hydrometers are calibrated at 60°F (15.5°C) or 68°F (20°C). A warm sample reads low: at 100°F a 60°F-calibrated hydrometer under-reads by about 0.005. Either cool the sample or apply a temperature correction.
- Record OG before pitching yeast, and FG only when readings are identical two or three days apart — that stability, not the calendar, says fermentation is done.
Specific gravity to potential alcohol chart
Read before fermentation, this chart estimates the alcohol you would get if the batch fermented all the way to 1.000. It is the quickest way to sanity-check a recipe's target strength.
| Specific gravity | Potential ABV | Specific gravity | Potential ABV |
|---|---|---|---|
| 1.010 | 1.3% | 1.070 | 9.2% |
| 1.020 | 2.6% | 1.080 | 10.5% |
| 1.030 | 3.9% | 1.090 | 11.8% |
| 1.040 | 5.2% | 1.100 | 13.1% |
| 1.050 | 6.5% | 1.110 | 14.4% |
| 1.060 | 7.9% | 1.120 | 15.7% |
Brix, Plato and gravity
Refractometers read in Brix (°Bx), and many recipes quote Plato (°P). Both measure sugar content, and for wort they are close enough to treat as equal. A rough conversion to specific gravity: SG ≈ 1 + (Brix × 0.004) — so 12 °Bx ≈ 1.048 and 20 °Bx ≈ 1.080. Once fermentation starts, alcohol distorts a refractometer reading, so a raw Brix FG must be corrected before it goes anywhere near the ABV formula; a hydrometer FG avoids the problem entirely.
Can you calculate ABV without an original gravity?
Not from a hydrometer alone — the formula needs both ends of the journey. If you forgot the OG, your honest options are: estimate it from the recipe (grain bill and efficiency for beer, sugar/honey quantities for wine and mead usually land within a few points), or measure the finished drink with a refractometer and a hydrometer together and use a combined calculator. Anything else is a guess, and for strong drinks the guess can be a full percentage point out.
Frequently asked questions
How do I measure the ABV of homemade beer or wine?
You calculate it rather than measure it directly: take a specific gravity reading with a hydrometer before fermentation (OG) and again when fermentation has finished (FG), then apply ABV = (OG − FG) × 131.25. Home alcoholmeters (proof hydrometers) only work on distilled spirits, not beer or wine.
What is beer gravity?
Beer gravity is the specific gravity of wort or beer — its density compared with water (1.000). Sugars dissolved in wort push the reading up (a typical wort is 1.040–1.060); as yeast converts sugar to alcohol the gravity falls. The size of the fall is what determines ABV.
How do I test the ABV of a finished drink?
With a hydrometer FG reading plus your OG from brew day, use the formula. If you never took an OG, combine a refractometer reading with the hydrometer FG in a calculator designed for that pair — or send a sample for lab analysis if you need a number you can print on a label.
Can I calculate ABV without the original gravity?
Not accurately with a hydrometer alone, because the formula needs the gravity drop. Estimate the OG from your recipe quantities, or pair refractometer and hydrometer readings on the finished drink and use a combined correction calculator. Expect an uncertainty of roughly half a percentage point either way.
Why is my hydrometer reading different at warm temperatures?
Hydrometers are calibrated at a set temperature (usually 60°F or 68°F). Warm liquid is less dense, so the float sinks further and reads low — about 0.005 low at 100°F on a 60°F instrument. Cool the sample to near calibration temperature or apply a temperature correction before using the reading.
What final gravity should I expect?
Most beers finish between 1.005 and 1.015, dry wines and meads at 0.990–1.000, and sweet wines or meads anywhere from 1.010 to 1.030 depending on residual sugar. The number itself matters less than stability: the same reading three days running means fermentation is finished.
Skip the hand maths
The calculator runs both ABV formulas and the gravity conversions — and the rice guide covers the other kitchen ratio people look up here.