Using Hydrometers For Beer Fermentation Control

Hydrometers are tools used to measure specific gravity. Similar to thermometers, hydrometers feature a weighted base which floats in liquid being measured; higher readings indicate denser liquid with more sugar dissolved into it; brewing hydrometers may be referred to as saccharometers as they also compare density relative to sugar content in samples being evaluated.

Employing a hydrometer is easy. First, ensure your sample jar is clear of trub or sediment that could interfere with measurements. Next, drop in your hydrometer and give it a spin to get rid of any air bubbles before taking your reading; look for where the line crosses the liquid-air line to find your original gravity of wort; once fermentation has occurred you should take another reading to obtain its final gravity value.

Keep in mind that temperature will have an impactful influence on your specific gravity readings, and use math or an online tool to compensate if measuring at a different temperature than where your hydrometer was calibrated at. Please refer to your hydrometer’s instructions for information on which temperatures it has been calibrated at.