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For your aromatic brew


Coffee goal: a perfectly balanced taste! The digital refractometer SmartRef determines coffee %TDS and calculates the extraction yield with an in-app calculator to help you find the right balance between strength, acidity and sweetness for your coffee.

In combination with the mobile app Lab Meister measurement results can be managed and stored for later reference.

Lab Meister App for SmartRef Digital Refractometer TDS Measurement and Extraction Calculator for Coffee

With a small sample volume of only 0.4 mL, the SmartRef delivers accurate results with automatic temperature compensation (ATC):

  • Total dissolved solids [%TDS]
  • Brix [°Bx]
  • Refractive index current temp. [nD]
  • Temperature [°C], [°F]

The corresponding Lab Meister app offers additional in-app features like:

  • Automatic temperature compensation
  • Coffee extraction calculator
  • Data storage, management, visualization & export
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Elevate your coffee game with the SmartRef Digital Refractometer

Unlock the secrets to perfect coffee by measuring TDS and calculating the extraction yield with the SmartRef Digital Refractometer and the Lab Meister mobile app.

Brewing the perfect coffee is both an art and a science. Baristas understand that the pursuit of the perfect cup is a journey filled with experiments and refinements. Achieving an excellent balance of flavors, aroma, and body requires a deeper understanding of two critical parameters: Total Dissolved Solids (TDS) and the corresponding extraction yield. By mastering TDS measurement and extraction yield calculations, you can elevate your coffee experience and brew a coffee that perfectly fits your taste preferences.

SmartRef Digital Refractometer for Coffee, Roasters, Baristas to determine TDS and Coffee Extraction

Understanding TDS and coffee extraction yield

TDS (Total Dissolved Solids): This value describes the percentage of dissolved solids in your coffee. It indicates how much of the coffee bean has been dissolved and how concentrated or watery the coffee is. A stronger-tasting coffee, like espresso, has a higher TDS, while a weaker coffee, like filter coffee, has a lower TDS.

Typical TDS values:
Ristretto: > 12 %TDS
Espresso: 8 – 12 %TDS
Lungo: 2 – 8 %TDS
French press: 1.4 – 1.7 %TDS
Filter coffee: 1.2 – 1.5 %TDS

Extraction yield: This parameter provides insight into the extraction efficiency and the percentage of soluble coffee compounds that are extracted from the coffee grounds into the final brewed beverage. The gathered extraction yield quantifies coffee strength and taste.

Perfect your brew every time

Home-brewed coffee can vary in strength and flavor. For consistent, delicious results, consider these factors:

  • Grind size: The grind size significantly influences TDS and extraction yield. Finer grinds produce a more intense flavor and stronger coffee with higher TDS, while coarser grinds result in a lighter brew with lower TDS.
  • Extraction time and type: The extraction time defines how long water is in contact with the coffee grounds. A commonly recommended range for espresso is 20 to 30 seconds, while methods like pour-over, French press, or AeroPress can range from 2 to 4 minutes. Longer extraction times lead to higher concentrations of dissolved substances and bolder flavors.
  • Water temperature: The temperature of the water affects both TDS and extraction yield. Too hot water may extract bitter flavors, while too cold water may cause incomplete extraction. The right water temperature, synchronized with grind size and extraction time, is crucial for your perfect coffee.

Improve your coffee taste with the SmartRef Digital Refractometer

In combination with the Lab Meister mobile app, the SmartRef measures the TDS value of your coffee with an accuracy of ±0.2 %TDS. The app offers two exceptional ways to determine TDS (Total Dissolved Solids). You can choose between a fixed calculation (%TDS) or a custom calculation (%TDS custom), where you have the flexibility to set your own calculation factor. The in-app coffee extraction calculator helps you to fine-tune your variables and create a coffee that matches your desired taste and strength.

Measure Coffee TDS and Extraction Yield with the SmartRef Digital Refractometer

How to measure TDS with the SmartRef:

  1. Prepare your sample: Stir your coffee sample thoroughly to ensure homogeneity. Fill a syringe or pipette with the hot coffee and cool it to room temperature. Cap the syringe to minimize evaporation during cooling.
  2. Prepare for measurement: Clean the prism and pipette coffee into the sample well.
  3. Start the measurement: Choose %TDS or %TDS custom and start the measurement.
  4. Save your data: Log and maintain a record of your sample.

How to calculate the extraction yield with the Lab Meister mobile app:

  1. Open the coffee extraction calculator within the ‘Tools’ section and select your brewing method: Espresso, French Press, or AeroPress
  2. Perform the calculation: Enter the weight of your coffee grounds and the weight of brewed coffee or water used (depending on the method). Import the TDS value from the log and start the calculation.
  3. Analyze your results: The app provides the extraction yield and additional information on whether your coffee is optimally extracted, over-extracted, or under-extracted, as well as your coffee-to-water ratio.

Discover the SmartRef advantage

Dive into the world of coffee art with the SmartRef Digital Refractometer and explore the interplay between grind size, temperature, and extraction. Each measured TDS value and calculated extraction yield brings you closer to your perfect brew.

Brew like a barista and elevate your coffee experience!

Coffee TDS measurement with SmartRef Digital Refractometer

Coffee TDS measurement with SmartRef Digital Refractometer

The TDS value describes the amount of the total dissolved solids in a sample in percent. Simply put, it describes how much of the coffee bean has been dissolved into your coffee and how concentrated (strong) or watery (weak) the coffee is.

This makes it possible not only to speak subjectively about the strength of the coffee, but also to make the taste measurable.

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Device features

High accuracy

High-precision measurement sensor with an accuracy of 0.2 °Brix

Wide measuring range

Measuring range from 0 to 85 °Brix with automatic temperature compensation


Free mobile app for iOS & Android with smart measurement guidance for precise results

Waterproof design

IP66 dust-tight and protected against powerful water jets

Why SmartRef?

Other refractometers
One device for all units
Continuous measurement mode
Simple cleaing & adjustment
Sample verification for reliable results
Smart data management via mobile app
Over-the-air updates with new features & scales
Automatic in-app calculations
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