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Advancements in technology have led to innovative inventions in every aspect of life as we know it. Not surprisingly, the world of coffee making is not far behind. Today, we have a Coffee Refractometer that can help you take your coffee-brewing precision to the next level — whether you’re a coffee company or a passionate coffee lover.

Like any other refractometer, the coffee refractometer gives you more insight into the specific properties of your coffee, such as how much extraction has occurred.

But, how exactly does this unique coffee tool work?

In the following paragraphs, we explore what the coffee refractometer is and how it arrives at its results. You’ll also gain insight into the various types of coffee refractometers and how to use them.

So, let’s dive into it.

What is a Coffee Refractometer?

Digital coffee refractometer

Conventionally, refractometers are a scientific device, and you will typically find them in science laboratories globally. However, they do have some applications in the coffee-making scene.

But, first, let us examine what a refractometer itself is.

A refractometer is a device that measures the refraction of light from the air through a liquid. In other words, it measures how light bends when it goes through the boundary between the atmosphere and the liquid. Measuring this refraction can provide more specific information about the liquid in question.

In the same way, a coffee refractometer can give you insight into the properties of brewed coffee by measuring light refraction through it. The device then comes up with a TDS (Total Dissolved Solids) value for the coffee, thereby allowing you to calculate its extraction yield.

In this case, the total dissolved solids are the roasted and ground coffee bits dissolved in the hot coffee water.

That said, some coffee refractometers will directly provide you with values for both the TDS and extraction yield. However, if yours doesn’t, there is an easy way around this problem. Using this formula will help you calculate your extraction yield:

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

Of course, you probably already know that your extraction yield plays a critical role in how your coffee tastes. So, by experimenting with your TDS value, extraction yield, and recipe, you can work your way to brewing stronger coffee that appeals better to your nose and taste buds.

How to Use a Coffee Refractometer?

While the science behind a refractometer for coffee may be somewhat complex to navigate, using the device itself is significantly more straightforward. 

The most challenging part about using a coffee TDS refractometer may be acquiring it in the first place, especially if you are not using it for business. This is because most coffee refractometers will cost around $150!

However, if you already have one, then you’ve done the hard part. Now, we’ll walk you through the rest.

Here’s how to use a coffee refractometer:

  • First, reset the refractometer to zero by using distilled water to re-calibrate it. Note that you don’t necessarily have to do this before every reading. Once a day should be enough.
  • Once you’ve reset the refractometer, you need to stir your coffee very well before you take a reading (coffee stratifies extremely fast).
  • Next, use a pipette to get a small sample of the coffee.
  • Then, pipette this coffee sample onto the refractometer glass such that coffee covers the entire glass.
  • Wait for a few moments, usually 15 to 20 seconds.
  • Close the lid on the refractometer and press ‘Go’ or ‘Run,’ depending on your model, and wait until the device displays the same TDS reading three consecutive times.
  • Use a tissue to dry the glass.
  • Then, wipe the refractometer glass clean with some alcohol.

Pro Tip? This procedure only works best if you’re measuring filter coffee.

If you want to measure espresso, you’ll need to first filter the sample to remove CO2. Then, you can then use a syringe to take a smaller espresso sample and push it onto the refractometer coffee class through another filter.

Coffee Refractometer Basics By RealChrisBaca

How to Boost Your Coffee TDS Refractometer Values?

What happens when the values you get on your Coffee TDS refractometer are lower than you’d like? 

You can manipulate your coffee brewing process to boost your TDS value, improve your extraction yield numbers, and get higher quality coffee in terms of flavor and taste.

Here are some tips on increasing your coffee refractometer TDS readings and achieving better coffee:

Increase your coffee-to-water ratio

This is the most straightforward way to increase the strength of your coffee and, subsequently, your TDS value. But, using more coffee in relation to the amount of water you previously used will get you a higher TDS reading.

Use finer coffee grounds

Grinding your coffee to finer bits will increase its surface area and ensure more water can get in there to extract more coffee ‘juice.’ For instance, cutting a coffee bean in half doubles its surface area, which means extracting from it becomes twice as easy. 

Of course, better coffee extraction means an increase in the strength of the brew.

Increase your brewing temperature

Higher thermal energy during the coffee brewing process improves the rate and efficiency of extraction. This, in turn, leads to coffee with higher strength and increased TDS.

Use a higher stir rate when brewing

Stirring while brewing your coffee will cause turbulent movement in the coffee bed and move the grounds around in the water. Depending on how turbulent this motion is (the speed of your stirring), you’ll expose more coffee grounds to the hot water, which means you get better extraction and stronger coffee. In other words, more turbulence equals stronger coffee.

Try to avoid channeling

Channeling in coffee making means running water through your coffee bed unevenly, and it leads to under-extraction, which means watery coffee. Nobody wants this. Thankfully, using the correct coffee ground dosage and correctly tamping are great ways to prevent channeling while you brew.

Types of Coffee Refractometers

Several options are available to you when you shop for coffee refractometers. However, there are two common refractometers for coffee that you’d typically find:

1. Digital Coffee Refractometer

The digital coffee refractometer is one of the most common options for measuring TDS in the barista scene. However, digital coffee refractometers can typically do more than measure TDS. For example, most models can also measure the amount of sugar in your coffee.

In other words, you get a device that measures both the concentration of your coffee (Total Dissolved Solids) and the amount of sugar in the brew (Brix degree). Additionally, digital coffee refractometers can also measure the temperature of your coffee if you also want this data.

Here are the measurement ranges you’d typically find on a digital coffee maker refractometer:

  • TDS: from 0.0% to 23.0%
  • Brix degrees: from 0.0% to 26.0%
  • Temperature: from 0º to 70ºC

We should also mention that the digital coffee refractometer is the most expensive type of refractometer for coffee however, over the last couple of years they have become more affordable. Check them out here or click the big orange button below:

2. Optical Coffee Refractometer

Unlike their digital counterparts, optical coffee refractometers are typically smaller (think about a larger-than-normal thermometer). However, this also means they are more affordable too.

There’s a drawback though.

An optical coffee refractometer will only measure the sugar concentration in your coffee and will not give you a value for its TDS. In other words, this refractometer can only get Brix degrees readings.

On the bright side, optical refractometers have a greater measuring range for sugar concentration compared to digital refractometers. Check them out here or click the big orange button below:

Coffee Refractometer Overview: The Pros and Cons

No doubt, coffee refractometers offer their users a more detailed insight into the quality of the coffee they’re brewing. But, should you buy one? 

Well, there is no right or wrong answer. But, let us examine some of the advantages and drawbacks that come with owning and using a coffee refractometer. This way, you have more information to help you decide whether you invest in a refractometer or not:


  • It helps businesses such as coffee shops and roasteries to ensure consistency in their brews
  • Coffee refractometers help to guarantee high-precision brews and have your better insight into the quality of your coffee
  • It provides concrete data for the analysis and evaluation of coffee from new sellers. This way, you can better inform your source or switch options 
  • A coffee refractometer will indicate whether your coffee is under or over-extracted


  • A good coffee refractometer is an expensive upfront investment as the device itself and its accompanying accessories can easily cost $800. The mobile software can cost up to $50 while the PC/Mac versions cost around $150
  • It is impractical for personal use due to its high costs
  • It does not indicate what exactly was extracted, only how much extraction occurred. However, simple tasting should solve this problem — under-extracted coffee has a sour taste while over-extracted coffee is usually bitter


What does a refractometer measure in coffee?

A coffee refractometer measures the amount of total dissolved solids in your coffee. This gives you an idea of how much extraction took place during the brewing process and indicates how strong the coffee is.

What is the difference between TDS and Brix?

TDS is the measure of the total dissolved solids in a coffee sample while Brix measures the concentration of sugar in that sample.

How do you use coffee TDS?

You can use coffee TDS refractometer values to optimize your coffee brewing process until you get coffee with the desired strength. In other words, the higher the TDS reading you get, the stronger your coffee is.

Bring It Home

While a coffee refractometer can undoubtedly be an investment with serious financial implications (especially for individuals), the device also comes with many advantages. For instance, a refractometer may be the key to achieving high-precision coffee brews, with consistent taste and flavors.

Despite this, it is quite understandable that not everyone will buy a coffee refractometer. 

But, if you’ve decided that a refractometer is an investment you want to make, make sure you check out the Atago 3810 here:

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