Coffee TDS (Total Dissolved Solids) Explained

TDS may seem (or sound) like a very technical term. But in reality, it is basically the amount of coffee that ends up in your cup. Yep, it’s that simple! 

TDS stands for Total Dissolved Solids, and it refers to the ratio of ground coffee particles that get carried from your ground up coffee beans, into the cup of coffee you end up drinking. 

TDS refers to the dissolved solids in coffee, including the flavour compounds, minerals, and organic matter that contribute to its overall taste. Measuring TDS helps coffee professionals evaluate the extraction process, quantify the strength, understand the balance of flavours, and ensure consistency in each cup. 

But in essence, the home barista can think of TDS as coffee ‘strength’, referring to the intensity and concentration of their coffee and water solution. 

TDS is generally expressed as a percentage. So if you have 100g (ml) of water, with 1g of coffee solids mixed in, you’ll have a TDS of 1%. 

In this article, I will explore how TDS measurements are taken, the ideal range for various brew methods, and how to optimise your coffee extraction. Whether you are a home brewer or a coffee professional, this guide will help you unlock the power of coffee TDS and become a better brewer. 

What is Total Dissolved Solids (TDS) in Coffee?

Total Dissolved Solids (TDS) refers to the dissolved solids in coffee, including the flavour compounds, minerals, and organic matter that contribute to its overall taste. 

This comes down to the actual ‘coffee’ that you extract from the ground beans that ends up in your cup (diluted with water). 

Measuring TDS helps coffee professionals evaluate the extraction process, quantify the strength, understand the balance of flavours, and ensure consistency in each cup. It also helps home brewers understand why their coffee may taste too bitter, too weak or just plain wrong!

Coffee TDS is typically expressed as a percentage, which represents the ratio of the mass of dissolved solids to the mass of the coffee beverage. A TDS of 10% means that for every 100 grams of brewed coffee, there are 10 grams of dissolved solids. The higher the TDS, the stronger and more concentrated the coffee will be.

By understanding TDS, you can make informed decisions about brewing variables such as grind size, water quality, extraction time, and brewing temperature.

How to Measure TDS in coffee

Measuring TDS is crucial for both coffee enthusiasts and professionals. It provides valuable insights into the brewing process and allows for adjustments to achieve the desired flavour profile. 

For coffee professionals, measuring TDS is essential for quality control and consistency. It helps them ensure that every cup of coffee they serve meets their standards and provides a consistent experience for their customers. By monitoring TDS, professionals can identify any issues with the brewing process and make necessary adjustments to optimise extraction.

Measuring TDS in coffee can be done using a TDS metre, which is a device specifically designed for this purpose. TDS metres work are otherwise known as refractometers, which use light sensors to measure the refraction of light through water, and therefore determine how much ‘resistance’ there is in the liquid. 

RS Online put it better than me, explaining how “refractometers measure the extent to which a beam of light bends when it passes through a transparent substance…assess(ing)… the concentration of any substances which have been added” in their article titled “A Complete Guide to Refractometers” – Jan 2023. 

416 Coffee Company also does a great job of breaking down what TDS is and provides a practical demonstration of how to measure the TDS of coffee with a refractometer.  

Fellow have also done a great step by step breakdown that you can follow along with if you are looking to measure TDS at home. 

Tips for Measuring TDS: 

Here are a few helpful tips for measuring TDS at home: 

• Make sure your coffee is as close to room temperature as possible
• Stir your coffee to ensure it is homogenous
• Clean your refractometer with an alcohol swab before use
• If you are comparing coffee shots, try and keep your brewing conditions (time, temperature, grind size etc) as consistent as possible. 

For a more in depth and scientific look at TDS, extraction yield and time range, check out Whole Latte Love’s video breaking all this down here: 

AJ does a fantastic job of distinguishing between strength (TDS) and extraction (the amount of your coffee puck that ends up in the cup, and how these are inversely correlated. 

This may sound odd, but it actually makes sense when you think about it. 

Strength refers to the ratio of water to coffee solids, which is what we mean when we refer to TDS. Whereas, extraction refers to the amount of soluble material removed from the ground coffee puck. 

So, the higher your TDS percentage, the lower the amount of coffee that’s left behind in the puck. 

Factors That Impact TDS in Coffee

Several factors can affect the TDS of coffee, and these are the variables you’ll want to play around with when adjusting the strength of your coffee up or down. Here is a breakdown of the most influential factors that impact your coffee’s TDS. 

1. Coffee-to-Water Ratio: The amount of coffee used relative to the amount of water will impact the TDS. A higher coffee-to-water ratio will result in a higher TDS, leading to a stronger and more concentrated brew.
2. Grind Size: The size of the coffee grounds affects the extraction rate and, consequently, the TDS. Finer grind sizes increase the surface area of the coffee, leading to higher extraction and a higher TDS.
3. Water Quality: The mineral content and pH of the water used for brewing can influence the TDS. Water with high mineral content tends to extract more solubles from the coffee, resulting in a higher TDS.
4. Extraction Time: The duration of the brewing process impacts the TDS. Longer extraction times allow for more solubles to be extracted, leading to a higher TDS. What’s more, the timing of when you measure TDS will have an impact, as the coffee extracted from the start of an espresso shot will have a much higher TDS than that at the end. 
5. Coffee Roast: The degree to which your coffee is roasted also impacts TDS. Since darker roasts are more porous and contain more soluble material, they tend to have a higher TDS than lighter roasts.

Ideal TDS range for different coffee brewing methods

The recommended level of TDS will vary between coffee brewing methods, but as an example, espresso generally has a TDS of 15-30%, whereas brewed coffee (french press, pour over etc) sits at 1-1.5%. Generally you’ll want to be shooting for 1.35% to be specific when it comes to brewed coffee, and 18-22% for espresso. 

As mentioned above, it’s important to note that the ideal TDS range can vary based on factors such as coffee bean origin, roast level, and flavour profile. Therefore, it may take a bit of trial and error to dial in your perfect level of TDS when you change coffee beans, brewing equipment or even ambient conditions. 

Here are recommended TDS ranges for some popular brewing methods. These are guidelines, so remember to experiment with your own refractometer at home and most importantly, taste your coffee frequently to find out your personal preferences! 

1. Pour-Over: For pour-over brewing, a TDS range of 1.25% to 1.35% is often sought after. This range allows for a well-balanced cup with a good extraction of flavours.
2. Espresso: Espresso requires a higher TDS to achieve the desired strength and richness. The recommended TDS range for espresso falls between 18% and 22%.
3. French Press: French press brewing typically results in a higher TDS due to the longer extraction time. A TDS range of 1.35% to 1.45% is commonly recommended for French press coffee.

Adjusting TDS in Coffee

Achieving the perfect TDS for your coffee can be a matter of personal preference. Whilst the guidelines above generally provide a golden ratio of 1.35% for brewed coffee and around 20% for espresso, you can adjust your coffee’s TDS to your preferences. By adjusting various brewing variables, you can fine-tune the TDS to achieve your desired flavour profile, be that stronger or less intense. 

Here are a few ways to adjust your coffee TDS with ease:

1. Coffee-to-Water Ratio: Increasing or decreasing the amount of coffee grounds or water used can directly impact the TDS. Experiment with different ratios to find the right balance, but the more coffee you use, the more that can be extracted. 
2. Grind Size: Adjusting the grind size can affect the extraction rate and TDS. Finer grinds will increase the TDS, while coarse grinds will result in a lower TDS.
3. Extraction Time: Shortening or lengthening the brewing time can influence the TDS. A longer brew time will increase the strength of your coffee (TDS), but it is worth noting that the level of coffee extraction will tail off quite rapidly as time goes on. 
4. Water Quality: Using different types of water with varying mineral content can also impact the TDS. Consider using filtered or bottled water to achieve consistent results, taking out the variables of geographical water hardness. 

Common Misconceptions about TDS in coffee

There are some common misconceptions about TDS in coffee that should be put to bed. Whilst it may seem technical, it doesn;t have to be complicated or confusing. Here are a few common misconceptions about the TDS of your coffee. 

1. Higher TDS means better coffee: While a higher TDS can indicate a more concentrated and stronger brew, it doesn’t necessarily mean better coffee. The ideal TDS range varies based on personal preference and the brewing method. If anything, increasing your coffee’s TDS runs a greater risk of a bitter cup of coffee.

2. TDS determines coffee quality: TDS is just one of many factors that contribute to coffee quality. Other factors, such as bean quality, roast level, dose and freshness, also play crucial roles in how good your coffee tastes. 
3. TDS alone determines coffee strength: TDS provides an indication of coffee strength, but it doesn’t tell the whole story. The perception of strength is also influenced by factors such as aroma, bitterness, and acidity. The coffee’s roast level and how the coffee is served (what additional ingredients are added like milk or sugar) also play a huge role in how ‘strong’ the coffee will taste. 

Summary

Overall, Total Dissolved Solids (TDS) is a crucial metric in determining the strength or concentration of your beloved cup of coffee. 

By understanding and measuring TDS, you can gain valuable insights into the brewing process, optimise extraction, and achieve the perfect cup of coffee. 

Whether you are a home brewer or a coffee professional, understanding the TDS of your coffee can help you control the variables and really dial in the perfect coffee to water ratio for you. 

TDS is not the be all and end all of coffee brewing, so unless you are a coffee professional that wants to take customer service to the Nth degree, or a real coffee nerd, don’t get bogged down in the details. 

Let me know your experience with TDS and whether you find it to be a useful measure in home coffee brewing. 

Coffee TDS Frequently Asked Questions

What is TDS in Coffee?

TDS, or total dissolved solids, is the amount of soluble coffee solids that end up in the brewed water that we call ‘a cup of coffee’. 

What is a Good Level of TDS in Coffee?

Generally speaking, brewed coffee (filter, french press etc) should have a TDS of around 1.35%, whereas espresso should sit closer to 20% TDS. 

How to Adjust TDS in Coffee?

There are a number of ways to influence the TDS of your coffee, including dose, grind size, extraction time and the water used.