Refractometer vs Hydrometer: Which Should You Use?

When it comes to brewing beer, one of the main ways brewers ensure they are being consistent and improving the quality of their beer is by measuring its specific gravity. Always looking to improve upon your brewing skills can make the difference between an okay beer and a great one. In this article, we are going to compare Refractometers vs Hydrometers, both of which can be essential tools in the brewer’s arsenal that help to evaluate the brewing process and make quality beer.

What are Refractometers and Hydrometers?

Refractometers and hydrometers are the tools used to measure specific gravity during the brewing process. The readings taken with these tools allow a brewer to:

– Determine if they are hitting the gravity targets for the recipe they are brewing

– Calculate the efficiency of the mash

– Take readings during fermentation to watch its progress and determine when it has finished

– Calculate the ABV or alcohol percentage of their beer

Refractometer vs Hydrometer

Novice brewers often make the mistake of thinking that a hydrometer and a refractometer are pretty much the same tools and do the same thing; however, the reality is although they both take gravity readings, they differ in how they take the readings as well as when the readings can be taken.

A hydrometer measures the actual density or specific gravity of the liquid by displacing a sample of the liquid, while a refractometer uses light to measure the amount of sugar in the liquid. 

A refractometer next to a hydrometer in front of pints of beer next to the words refractometer vs hydrometer.
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Neither tool is really better than the other, and the choice often comes down to the brewer’s personal preference. Although as you will see if you use a refractometer, you will also need to use a hydrometer. Whereas a hydrometer can be used in all cases.


The most well-known tool and most used out of the two is the hydrometer, which measures wort and beer’s specific gravity. This simple and inexpensive tool is very effective in dialing in gravity readings.

To use a hydrometer:

– Place it directly into the liquid.

– The hydrometer floats, displacing the liquid.

– The hydrometer’s position in the liquid determines the Specific Gravity reading.

– Take your reading where the liquid meets the scale on the side of the hydrometer.

Hydrometers require that the liquid is at a certain temperature for accurate readings, which is usually room temperature. Be careful not to allow the liquid to get too warm, as the warmer it is, the less dense it will be, which can lead to an incorrect reading.

To use this tool, you will also need a beer thief, or a graduated cylinder, as well as a thermometer to make sure the sample of wort is at the right temperature.

Although a hydrometer is an effective tool, it does have some drawbacks. The biggest drawback is that it requires larger sample sizes of the wort or beer to be pulled from the fermenter every time you take a reading. So depending on how many readings you take, it can mean you are wasting a fair amount of beer.

Moreover, you can risk contaminating your beer if you return the wort back into the fermenter (which we don’t recommend you do!).


A refractometer measures the refraction of light passing through a liquid. It is more expensive than a hydrometer but requires a smaller sample size.

To use a refractometer:

– Place a few drops of liquid on the prism surface of the refractometer.

– Look through the eyepiece to read the Specific Gravity.  It helps to aim the refractometer at a light source.

One drawback of refractometers is that they are not accurate during or after fermentation due to the presence of alcohol in the liquid. You need to use a hydrometer to measure the final gravity and calculate the ABV.

Last Call

As you can see, refractometers and hydrometers are useful tools for measuring the sugar content of liquids, such as wort, during the brewing process. Refractometers are more accurate, require less liquid, and are faster than hydrometers, making them the preferred choice for many brewers. However, they require calibration and are less effective at measuring final gravity.

Hydrometers are less expensive and do not require calibration, making them a good option for beginner brewers. They also allow for more accurate measurements of final gravity. However, they are more fragile and require a larger sample size, which can be inconvenient.

Ultimately, the choice between the refractometer vs hydrometer comes down to personal preference and the specific needs of the brewer. Both tools have strengths and weaknesses, and choosing the right one will depend on accuracy, ease of use, sample size, and cost.

Regardless of which tool is used, it is important to ensure that it is properly calibrated and used correctly in order to obtain accurate measurements and produce high-quality beer.

P.S. Be sure to pick up your gift of Big Robbs’s top 5 favorite beer recipes from his brewpub. Details are on the side of the blog or at the bottom if you are on your phone. Cheers!

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