Quick answer
- Take a hydrometer reading before adding the yeast and another when fermentation is finished.
- Alcohol % ≈ (starting S.G. − final S.G.) ÷ 0.0074.
- Example: 1.080 to 0.995 gives about 11.5% alcohol.
Want to know how strong your wine is? All you need is a hydrometer and two readings. Which method you use depends on the scales printed on your hydrometer. A triple scale hydrometer has all three.
Method 1: The Specific Gravity Scale
- Take a reading just before you add the yeast.
- Take a final reading once fermentation is finished, before you add any sweetener.
- Subtract the final reading from the starting reading.
- Divide the result by 0.0074.
| Example 1 | Example 2 | |
|---|---|---|
| Starting S.G. | 1.070 | 1.080 |
| Final S.G. | 0.995 | 0.995 |
| Difference | 0.075 | 0.085 |
| ÷ 0.0074 | about 10.1% | about 11.5% |
Method 2: The Potential Alcohol Scale
Take the same two readings, but on the potential alcohol scale. Subtract the final number from the starting number. The difference is your approximate alcohol content.
Method 3: The Brix (Balling) Scale
Brix measures the percentage of sugar in the juice. One degree Brix equals 1 g of sugar per 100 ml (10 g per litre). Take a reading before adding the yeast. As a quick rule of thumb, divide the Brix by 2 and add 1 to estimate the finished alcohol. Treat this as a rough estimate. The S.G. method above is more precise.
Forgot Your First Reading?
Without a starting reading you cannot calculate the alcohol content. A vinometer can help. It is a small, inexpensive tool that estimates the alcohol in finished wine. It is fairly accurate for dry wines and less accurate for sweet ones.
New to hydrometers? Start with How to Use a Hydrometer for Winemaking.
Frequently Asked Questions
How much alcohol is in a wine kit?
Most wine kits finish between about 11% and 14% alcohol, depending on the style. Lighter kits can be around 7%. The kit box lists the target.
Should I take the final reading before or after sweetening?
Before. Adding sweetener raises the S.G. and throws off the calculation.
Does topping up with water lower the alcohol?
Topping up to the 23 L mark is part of the recipe and is already built into the kit’s target. Take your starting reading after topping up.
Need a hand with your batch? Call us toll-free at 1-877-668-6160 (Monday to Friday, 8:00 a.m. to 3:00 p.m. Eastern) or send us a message.
This guide is adapted from the ABC Crafted Series booklet Wine From Kits: What the Instructions Don’t Always Tell You. Always follow the instructions that come with your kit.