What Is Coffee Concentration or Coffee TDS?

In coffee recipes, we often indicate the TDS of a beverage. To clarify what this means, we decided to write this article.

TDS stands for Total Dissolved Solids. It is a measure that indicates how concentrated your coffee is. TDS is expressed as a percentage. For example, if a drink has a TDS of 1.40%, this means that 1.40% of the beverage consists of dissolved substances from coffee, and the remaining 98.60% is water. The higher the TDS, the more concentrated the coffee.

TDS is measured using a refractometer. To determine the TDS, you place coffee on the lens and wait for the result. The device has only two buttons: Start and Zero. The “Zero” button is used to calibrate the refractometer. To do this, you pour distilled water (with a TDS of zero), press “Zero,” and that sets the starting point for measurements.

If you prefer more concentrated coffee but the recipe gives a lower TDS, you can adjust it by changing the coffee-to-water ratio. This parameter is highly sensitive to that ratio, so changes should be made gradually. Another way to influence TDS is by adjusting the grind size or pour technique—for example, stretching the pour time, or using pulse pours (e.g., adding 50 grams at regular intervals). This extends extraction time and may increase concentration.

Since water makes up the majority of a coffee beverage, you can also influence TDS through water quality. Using water with higher mineral content will usually lead to a higher TDS. There are separate devices for water: conductometers and TDS meters—they measure water mineralization. However, do not confuse these with refractometers.

It’s important to remember that TDS does not reflect quality characteristics of the drink—it only shows how many coffee solids are dissolved in the liquid. It doesn’t reveal which substances are present—just their quantity. TDS is only one parameter of a coffee drink.

Another important parameter is extraction yield—this speaks to the quality of the brew: how much flavor was extracted from the coffee. It’s also measured as a percentage and is calculated using this formula.

According to the Specialty Coffee Association, the ideal extraction yield range is 18–22%.

• If it’s below this, it’s under-extracted—you haven’t brewed out everything you could from the coffee.

• If it’s above 22%, it’s over-extracted, meaning bitter compounds are being extracted.

It’s important to find the golden middle.

TDS, however, doesn’t have official standards—it depends on personal taste. Some people prefer more concentrated coffee, others less. Cultural differences also play a role.

If you don’t have a device at home, that’s okay. You can evaluate concentration by taste—just pay attention to what you like or dislike and adjust accordingly.

However, in professional coffee brewing, especially in cafés, we recommend buying a refractometer. It’s a great tool for controlling beverage quality.