How to Read a Hydrometer for Wine

A hydrometer helps a winemaker determine how much sugar is in their wine.

Next to the grapes themselves, a hydrometer is the most essential tool a winemaker must have to be successful. The hydrometer, when used properly, can tell a winemaker how much alcohol is present in his wine before and after the fermentation process. Hydrometers measure the weight of a liquid (also known as specific gravity) compared to the normal weight of water. Properly calibrating the hydrometer and knowing how the ratio of sugar in wine translates to alcohol content will allow you to read a hydrometer.

Things You'll Need

• Distilled water
• Glass jars
• Instant read thermometer
• Wine thief

Instructions

1. Pour a small amount of distilled water into a clean glass jar and let it sit at room temperature. Check the temperature of the water using an instant read thermometer. Adjust the temperature of the water by putting it in the refrigerator briefly until it reads 60 degrees Fahrenheit.

2. Clean and sanitize all of your tools to be used in the testing process: hydrometer, wine thief and a slender glass testing jar. Handle the hydrometer gently as it is very fragile. Lightly dry using a clean cloth.

3. Place the glass jar on a flat, level surface.

4. Use the wine thief to draw a sample of wine or must. Make sure that the sample is free of any type of solid particles.

5. Fill the glass jar with enough liquid to allow the hydrometer to float in it without touching the bottom or sides.

6. Spin the hydrometer between your thumb and forefinger to release any air bubbles in the test sample. Place the hydrometer into the glass jar slowly.

7. Find the curvature line, or meniscus, of the wine's surface within the hydrometer and note the number where it appears. Refer to a chart that tells you what that number translates to in alcohol content. For example, a reading of 1.090 translates to an alcohol content of 12 percent.

Tips & Warnings

• To see how the fermentation of your wine is progressing, take a sample of the wine or must at the beginning of the process. You can check periodically and, if necessary, stop the fermentation process using Campden tablets once you have reached your goal.

References

• GrapeStompers: How to Use a Hydrometer in Winemaking
• The Winemaking Home Page; Using Your Hydrometer; Jack B. Keller Jr.; 2007

Resources

• GrapeStompers: Winemaking Conversion Calculators