What Does a Coffee Refractometer Do and How to Use It – It Matters!

Excerpt: This article provides in-depth information about coffee refractometers and how to use it. It also explains the pros and cons of using a coffee refractometer.

Coffee is one of the most common beverages taken in most parts of the world. A recent study found that around 166.63 million 60 kilogram bags of coffee were consumed in 2020/2021 worldwide. Entrepreneurs are now venturing into the coffee processing industry to meet the demands of coffee worldwide. There is also an increase in the number of coffee shops worldwide, which calls for new technologies for brewing the beverage and serving it to their customers.

Coffee is mainly brewed using milk or water. Some industries develop soluble coffee and package it in a small sachet that produces instant, mess-free coffee. Some love their coffee cold, while others like it when hot. Currently, several machines are used to test the quality of brewed coffee, such as the coffee refractometer. This article explains what a coffee refractometer does and how to use a refractometer.

What Is a Coffee Refractometer?

The basic principle of operation of the refractometer is in bringing up a reading of the total amount of dissolved solids (TDS).

Refractometers are machines used to check light refraction in different liquids. Lab experts also use a refractometer to test plasma levels and also check the composition of precious stones. Like the normal refractometer, coffee industries use this device to test the concentration of caffeine in coffee.

Most coffee roasters and top-level coffee shops have used coffee refractometers to ensure quality production in recent years. Some people who love brewing coffee also have these machines at home. Today, they are mainly used for quality control purposes and when beverage companies need to create a new brand.

Types of Coffee Refractometers

Digital Coffee Refractometers

Digital refractometers have an accuracy and precision between +/- 0.1 and +/- 0.2 Brix units.

Digital coffee refractometers measure both the Brix degree and TSD of the coffee. In addition, it also measures the beverage's temperature. It uses Bluetooth technology to record and send data through the application known as HM digital smart. The application is available on both android and iOS.

Digital coffee refractometers measure the following ranges:

  • TDS between 0% and 23%
  • Brix degrees between 0% to 26%
  • Temperatures between 0 degrees to 70 degrees

Optical Coffee Refractometers

Optical coffee refractometer is one of the inexpensive devices for home use.

Unlike the digital models, optical refractometers are smaller in size. They are also cheaper compared to the digital model. Optical refractometers only measure Brix degree, which is the sugar concentration. It does not measure TDS. However, the optical version has a broader range of measuring sugar concentration than the digital models.

What Does a Coffee Refractometer Do?

Beverage companies and high-end coffee shops use coffee refractometers to measure TDS or the Brix of coffee. To understand better, TDS is the total dissolved solids, while Brix is the total sugar concentration present in coffee.

By identifying these two values using the gadget, it is possible to know the exact amount of extracted coffee and caffeine concentration. Beverage companies use these machines to do the following:

  • To record data on the amount of sugar in coffee.
  • To measure the total dissolved solids and identify whether it is in the right concentration and not more or less diluted.

How to Calculate TDS?

The dissolved solids in your cup of coffee are the coffee parts that dissolve in the water while brewing. After taking measurements the one can use the formula below to calculate the amount extracted. However, with advancements in technology, most companies use applications to determine the amount of yield removed.


Extraction Yield % = Brewed coffee (g) TDS (%) / Dose (g)

The extraction level has a great impact on the coffee's taste and flavor. The best extraction yield should range between 18% and 22%.

One can adjust different attributes to increase the TDS percentage. Increasing the brewing time and pressure helps increase the total amount of solids dissolved. Fine coffee also has a high TDS.

How to Use a Coffee Refractometer?

Using this device is the best way to produce a high-quality cup of coffee. You can purchase a refractometer to help you make good coffee at home. Below is a guideline on how to use this device:

  1. Place a few drops or the beverage on the sample well
  2. Once you place these drops, the well lights up through the coffee sample
  3. After measuring, the device will display the data on the screen showing the total amount of dissolved solids
  4. As a barista, you will use the reading and the brewing procedure to come up with the right volume, enabling the machine to record data about the TDS and extraction yield
  5. Having all this information, one can adjust the recipe to create a perfect cup of coffee that you or your clients will love

Pros and Cons of Refractometers


  • It is a great tool, especially for coffee vendors or baristas. It helps them produce coffee that matches their client's needs.
  • The machine offers several ways to ensure precision and allow for in-depth analysis.
  • It indicates whether the coffee is too dilute or too strong and if it is over or under-extracted.
  • The measurements produced are essential in the evaluation of a new coffee brand from sellers. Coffee shops can use the device to inform the coffee producers to act on their grinding procedure to improve the quality of the coffee.


  • Refractometers are expensive, and coffee vendors will need to spend more money to buy one. The mobile application costs $30-$50, while the PC version costs $150. The gadget and all its accessories cost around $800.
  • It is only ideal for baristas working in high-end coffee shops. One cannot purchase the machine for home use purposes unless since it is an expensive tool.
  • It only displays the amount extracted but does not indicate what is obtained. This data is not very important since you can determine an under-extracted coffee by tasting it. Under-extracted coffee has a sour taste, while over-extracted coffee has a bitter taste.

Final Thoughts

The Milwaukee MA871 refractometer is equipped with an automatic temperature compensation function.

Coffee extraction is not the only factor that determines the quality of coffee. Some people love to brew unroasted coffee to their preference. Currently, coffee shops purchase the coffee refractometer to help develop quality coffee for their clients. Coffee vendors using this machine have noted an increase in sales since they produce coffee that matches the client's needs. It has led to a rise in profits.

In addition, it helps one produce the suitable precision that matches your taste. Before purchasing a refractometer, it is essential to research different types and choose more accurate results. According to several online reviews, most people prefer the MILWAUKEE'S instruments digital refractometer. Finally, all refractometers come with ready-to-install software that helps perform calculations such as the extraction yield and total dissolved solids.

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