How do I measure coffee TDS?
Measuring coffee TDS (Total Dissolved Solids) requires a digital refractometer. This device measures the concentration of coffee solubles in your brewed liquid, providing a percentage that indicates the strength of your coffee. By combining TDS with your brew ratio, you can calculate your extraction yield, a key metric in brewing science for ensuring consistent, high-quality coffee.
Measuring TDS is the gold standard for baristas and coffee professionals who want to move from 'guessing' to 'knowing' when it comes to their brew. TDS stands for Total Dissolved Solids, and it represents the percentage of the coffee liquid that is actually dissolved coffee material, with the rest being water. A typical cup of filter coffee usually has a TDS between 1.2% and 1.5%, while espresso is much more concentrated, often ranging from 8% to 12%.
To measure TDS, you need a digital refractometer, which uses light to determine the concentration of solids in a liquid sample. You simply place a few drops of your brewed coffee onto the sensor, and the device provides a reading. This number tells you how 'strong' the coffee is, but it doesn't tell you the whole story of the extraction. To understand if you have extracted the right amount of flavor, you must use the TDS reading to calculate the Extraction Yield.
Extraction Yield is the percentage of the dry coffee grounds that ended up in your cup. The industry standard for a balanced, well-extracted cup is typically between 18% and 22%. If your yield is below 18%, your coffee is likely under-extracted and sour. If it is above 22%, it is likely over-extracted and bitter. By using a refractometer, you can see exactly where your brew falls and make precise adjustments to your grind size or water temperature.
While this might sound like a laboratory experiment, it is a powerful tool for consistency. If you find a recipe that you love, measuring the TDS allows you to replicate it perfectly every time, regardless of minor variations in your technique. It removes the subjectivity of taste and gives you a concrete target to aim for, which is especially helpful when you are trying to dial in a new, expensive, or challenging coffee.
In practice, you don't need to measure every single cup, but using a refractometer occasionally is an excellent way to calibrate your palate. It helps you learn what a 1.3% TDS cup actually tastes like, so you can eventually judge strength by mouthfeel and flavor alone. It is an investment in your own skill as a brewer, turning the art of coffee into a repeatable, scientific process.
- · https://royalcoffee.com/understanding-extraction