October 23, 2018

How to Use a Refractometer

Learn how to use a refractometer to quickly measure sugar levels (Brix or gravity) in your beer or wine. Whether you're brewing, fermenting, or refining your all-grain technique, a refractometer helps you hit your numbers with just a couple drops of liquid.

How to use a Refractometer

What is a Refractometer?

A refractometer measures the sugar content of a liquid by analyzing how light bends through the sample. It performs a similar task to the hydrometer, but with faster readings and less wasted wort or wine.

Most refractometers display Brix, and some include a specific gravity scale. Ours does both, with automatic temperature compensation built in.

Benefits of Using a Refractometer

  • Requires only a few drops for fast, accurate readings
  • No need for a full test jar or hydrometer cylinder
  • Includes automatic temperature compensation (ATC)
  • Perfect for checking mash runoff, pre-boil gravity, and OG

How to Use a Refractometer

  1. Place 2–3 drops of wort or must on the prism surface
  2. Close the clear plate firmly
  3. Point the unit toward a bright light and look through the eyepiece
  4. Read Brix or Specific Gravity depending on the scale used

Note: For readings after fermentation (when alcohol is present), use our Refractometer Calculator to correct the final gravity.

How to Read a Refractometer for Final Gravity

Refractometers are less accurate after fermentation due to alcohol interference. Use your original Brix and final Brix readings in our free Refractometer Calculator to get an accurate final gravity and ABV estimate.

Frequently Asked Questions

What does a refractometer measure?

It measures sugar concentration (Brix) in unfermented wort, must, or juice by evaluating how much light bends through the liquid.

How do I convert Brix to Specific Gravity?

Use a dual-scale refractometer or input your Brix value into our online calculator for an instant SG reading.

Can I use a refractometer during fermentation?

Yes—but you must correct for alcohol with a final gravity calculator to ensure accuracy.

How do I calibrate a refractometer?

Use distilled water and the included screwdriver to adjust the zero line at room temperature.

Want to Learn More?

Level up your skills with Northern Brewer University and our video brewing courses.