A hydrometer is an instrument used to measure the specific gravity of liquid in comparison to pure water. The hydrometer is important because it allows a brewer to determine several things:

  • When the mash is no longer contributing sufficient levels of sugar during a sparge
  • How much dissolved sugar is in the finished wort
  • If your beer has under or over fermented
  • Brew house efficiency
  • Original gravity
  • Final gravity
  • Fermentation progress
  • Fermentation completion
  • Alcohol by volume.

Below are three examples of different hydrometers that are available to brewers, including one used for determining your final gravity.

Beer brewing hydrometers for taking specific gravity readings such as Original Gravity and Final Gravity

Beer brewing hydrometers for taking specific gravity readings such as original gravity and final gravity.

 

Here is the final gravity reading from a hydrometer that also registers temperature so that corrections can be made if the beer is too hot or too cold.

Beer Hydrometed, Final Gravity Reading

Beer hydrometer showing a final gravity reading.