Inputs
Use temperature-corrected readings from a well-mixed sample. Degas finished wine before measuring final SG.
Winemaking
Hydrometer ABV Calculator
Estimate finished alcohol from original gravity and final gravity hydrometer readings.
Estimate alcohol from hydrometer readings
This calculator is useful when you have an original gravity reading before fermentation and a final gravity reading after fermentation. It gives a planning ABV estimate from the gravity drop.
- Use original and final readings from the same gravity scale.
- Correct readings for sample temperature if your hydrometer requires it.
- Final SG should be stable before treating the ABV estimate as finished.
Hydrometer ABV notes
The standard formula is a practical estimate. Lab alcohol analysis is required for compliance, labels, or commercial decisions.
Carbon dioxide bubbles, suspended solids, temperature, and residual sugar can all affect final gravity readings.
Why final gravity still matters
A wine can show a large gravity drop and still contain residual sugar if fermentation stopped early. Conversely, a very dry wine can finish below 1.000 because alcohol is less dense than water.
If the final gravity keeps changing, fermentation is not stable enough for bottling decisions. Use the calculator after repeated readings are steady.
Before using the result on a full batch
Use this as planning arithmetic. Measure carefully, write down the assumptions, and make the smallest practical trial before a full cellar adjustment.
Best use
Estimating alcohol from OG and FG readings during home or small-lot winemaking.
Do not skip
Temperature correction, degassing, stable final readings, and lab analysis where required.
If the number looks surprisingly large or small, recheck every unit before acting. Most cellar mistakes start as unit mistakes.
How It Works
This calculator estimates ABV from original and final specific gravity readings.
- Enter original SG before fermentation.
- Enter final SG after fermentation has finished or stabilized.
- Review standard and alternate ABV estimates plus the reading note.
FAQ
Why is this only an estimate?
Hydrometer readings can be affected by temperature, CO2, sugar, alcohol, and measurement technique.
Can I use Brix readings instead?
Use a Brix or refractometer correction calculator if alcohol is already present.
What if final SG is above 1.000?
That can indicate residual sugar, an unfinished fermentation, or a style that is intentionally sweet.